---
title: 'HOSR Core Rules: Adventuring'
description:
date_pub: 2023-04-26T23:02:00-04:00
section: rules
content_type: feature
short_code: uha
---
[[toc]]
### Introduction
In general, playing an RPG powered by HOSR comes down to running through a series of linked procedures or "game loops":
1. **Setup**: GM determines the current situation (often using dice and tables), and describes it to the players.
2. **Response**: Players explain how they want to react to the situation, and make any checks that the GM calls for.
3. **Repeat**: Return to step 1 and repeat until the adventuring ends.
Some examples of these loops include the [Exploration Procedure](#exploration-procedure) or [Encounter Prodcedure](#encounter-procedure).
### Ability Checks
Simple tasks are assumed to succeed. If the task is dangerous or complicated, roll the dice for an Ability Check.
For most checks, roll a 20-sided die (d20) and add the ability's modifier.
| Ability | Mod |
| :-----: | :-: |
| 3 | -3 |
| 4-5 | -2 |
| 6-8 | -1 |
| 9-12 | +0 |
| 13-15 | +1 |
| 16-17 | +2 |
| 18+ | +3 |
[Ability Modifier]
- The GM may also add a situational modifier to the roll, typically between -4 and +4.
Then, check the results of the roll:
| Roll | Result |
| :----------------------: | :-----------------: |
| 25+ or natural 20 | Critical Success |
| 11-24 | Complete Success |
| 6-10 | Complicated Success |
| 5 or less | Failure |
| Less than 0 or natural 1 | Fumble |
[Ability Check Result]
- A natural 20 or a result of 25 or more is a **Critical Success**: the check succeeds, and often includes a bonus for the roller.
- An 11-24 indicates a **Complete Success**: the check succeeds.
- A 6-10 represents a **Complicated Success**: the check succeeds, but with a potential [complication](#complications) or challenge for the roller.
- A 5 or less is a **Failure**: the check fails.
- A natural 1 or a result of less than 0 is a **Fumble**: the check fails, and often includes an extra complication or challenge for the roller.
#### Skilled Ability Checks
Many classes have unique skills which PCs learn as they gain levels in those classes.
| Class Level | Mod | Term |
| :---------: | :-: | :------: |
| 1-3 | 0 | Beginner |
| 4-6 | +1 | Skilled |
| 7-9 | +2 | Advanced |
| 10-12 | +3 | Expert |
| 13+ | +4 | Master |
[Skilled Ability Check Modifier]
When making a check that involves a class skill, add the skill modifier for the PC's current level to the appropriate ability check roll.
- ex: a 5th level thief that wants to use their Thief Skills to hide in the shadows would make a DEX ability check, rolling a d20 and adding their DEX modifier to the roll, and would _then_ add an additional +1 to the roll before determining the result.
### Complications
Complications can effect the immediate situation or the GM can optionally save them for later, tallying or counting them, and making a Complication Check for each one at the next appropriate time.
#### Complication Check
Roll 1d6.
| 1d6 | Result |
| :-: | :--------------: |
| 1 | Encounter |
| 2 | Locality |
| 3 | Exhaustion |
| 4 | No complication |
| 5 | Signs / Portents |
| 6 | Discovery |
[Complication Check Result]
- **Encounter**: Wandering creature, social encounter, or some other random interaction.
- **Locality**: Some environmental or external event that affects the PCs.
- ex: a storm rolls in, party gets lost, the dungeon shifts, water rises, the assassin gets closer to the target, doors lock behind party.
- **Exhaustion**: Party must rest for a turn / watch or gain a level of [exhaustion](#exhausted).
- May be ignored for the first few checks in a session, as appropriate.
- **Signs / Portents**: Indications of possible encounter nearby - could be a clue, monster tracks, etc.
- **Discovery**: Party finds something useful or helpful.
- ex: a magic item, a secret door, a hidden ally.
- May be ignored after first occurrence in a session, as appropriate.
### Exploration Procedure
The time scales for exploration vary based on the area being explored:
- Dungeon exploration is divided into 10-minute turns, with each turn covering roughly 180 feet of unexplored dungeon.
- Wilderness exploration is divided into 4-hour watches, with each watch covering roughly 6 miles of unexplored (open) terrain.
The general steps to take when exploring (for each turn / watch):
1. **Setup**: GM describes the situation.
2. **Marching Order**: Party determines general exploration process, including direction of travel and speed.
3. [**Complication Check**](#complication-check): GM rolls the complication die to see what effect it has.
4. **Actions / Responses / Complications**: Party declares actions, GM describes the results (and any complications).
5. **End Turn / Watch**: When the party has gone far enough or combat has completed, the (dungeon) turn or (wilderness) watch ends.
6. **Repeat**: Return to step 2 and repeat until adventuring ends (or destination is reached).
### Challenges and Hazards
- Fall damage is 1d6 per 10'.
#### Darkness
- If unable to see, treat as [blinded](#blinded).
- Candles light 10' radius.
- Torches / lanterns light 30' radius.
- When moving through darkness with flame light, no chance of stealth / surprise.
#### Infravision
Allows creatures to see heat tones, even in [darkness](#darkness).
- Works to 60' unless noted otherwise.
#### Truesight
Allows creatures to:
- see in normal or magical darkness;
- see invisible creatures and objects;
- automatically detect, see-through, and Save vs visual illusions;
- perceive the true (original) form of a shapechanger or ploymorphed creature; and
- see into the ethereal plane to perceive ghosts and other spirits.
#### Listening for Noises
Spend a minute listening (ex: at a door) and make an [INT or WIS check](#ability-checks) to hear a noise.
- GM rolls.
#### Opening Doors
- Locked Doors can be picked or broken.
- Picking a lock takes up to 1d6 minutes.
- Stuck Doors can be unstuck or broken.
- To unstick or break a door, make a [STR check](#ability-checks) at -2.
- Doors always break on a critical success.
- Failure / complications can affect stealth / surprise.
#### Swimming
- Creatures are assumed to be able to swim at 1/2 their normal movement speed.
- Unless the creature is just floating, a [STR or CON check](#ability-checks) is required every turn (10 minutes).
- For creatures carrying heavy loads or wearing metal armor, this check is required very combat round (10 seconds).
- Failing this check results in a loss of 1 HP, and the check must be immediately attempted again.
- The third failure indicates the creature begins [drowning](#drowning).
##### Drowning
- Each combat round, a drowning creature must **Save** or take 1d8 drowning damage.
- When a drowning creature is rescued, it gains 1 level of exhaustion.
- Once the exhaustion is cleared, the creature gains back any HP lost to drowning.
#### Urban Navigation
To navigate to a location in a busting city, make an **Urban Exploration Roll** (2d6 + [CHA mod](#ability-modifier-table) + [INT mod](#ability-modifier-table)).
- Modify roll in friendly, dangerous, or especially alien areas.
- Navigation time includes time spent reading maps and getting directions, as well as any eating or rest stops needed along the way.
- Roll random encounter checks each hour.
| Roll | Result | Time Spent |
| :--: | :-------: | :--------------------: |
| 2 | Failure | Waste day searching |
| 3-5 | Wandering | Arrive after 2d4 hours |
| 6-8 | Success | Arrive after 1d6 hours |
| 9-11 | Fortunate | Arrive after 1d4 hours |
| 12+ | Direct | Arrive after 1 hour |
[Urban Exploration Results]
#### Wilderness Exploration
- Distances and non-magical ranges are tripled (yards rather than feet).
- Areas of breath weapons and spell effects are still measured in feet.
**Flight**
- Unless stated otherwise, flight distance is double that of overland travel.
- Flight speed is not affected by terrain.
- Winged beasts may be used as **mounts**, carrying riders or cargo based on the mount's HD:
- 3 HD: May carry a creature 1/2 the size of a humanoid.
- 6 HD: May carry a creature the size of a humanoid.
- 12 HD: May carry a large creature (ex: horse)
- 24 HD: May carry a huge creature (ex: elephant)
**Light**
- During the daytime, fog or heavy rain will create dim light in open areas.
- At night:
- A full moon on a clear night will create dim light in open areas.
- Fog or moonless night will create [darkness](#darkness).
**Overland Travel**
- The distance in miles that a character can travel overland in a day (16 hours) under normal conditions (and clear terrain) can be determined by multiplying their base movement rate by .6 (or 3/5).
- 10' / round => 6 miles / day
- 20' / round => 12 miles / day
- 30' / round => 18 miles / day
- 40' / round = 24 miles / day
- Some terrain affects overland speed while traveling through it:
- Maintained roads: Increase speed by 50%.
- Hilly, wooded, or desert terrain: Decrease speed by 33%.
- Swampy, mountainous, or jungle terrain: Decrease speed by 50%.
- Characters engaged in a forced march can increase their travel speed by 50%, but must rest for a full day or suffer 2 levels of [exhaustion](#exhausted).
- Characters can travel for up to 6 days before they must rest for at least 1 full day.
- For each day beyond the 6th that they travel without resting, they gain a level of exhaustion.
**Sight**
Characters can usually see 3 miles around (in clear terrain).
- Range of sight may vary based on terrain (ex: less in wooded area, more on an overlook).
### Encounter Procedure
1. **Check Stealth**: GM rolls for stealth, if applicable.
- Each side that's being relatively stealthy (quiet, douses torches, etc.) has a base 2-in-6 chance of not being spotted.
- Parties carrying an active light source typically can not have stealth.
- Individual party members may have stealth even if the rest of the party doesn't.
- If only one side has stealth, they may usually make a free attack (or can pass unnoticed).
- If all sides have stealth, they miss each other.
2. **Determine Distance**: GM determines how far away the characters are from the encounter.
- Often determined by the nature of the encounter itself, but may be determined randomly:
- Dungeon: 2d6 x 10'
- Wilderness: 4d6 x 10 yards (or 1d4 x 10 yards if either side is surprised).
3. **Roll Initiative**: Each side rolls 1d20, highest roll moves first.
- Tie goes to the party side, roll-off as needed.
4. **Choose Actions**: Each side decides how they will respond in initiative order, and the encounter proceeds.
- Players decide how their characters will act.
- Creature actions are often determined by the nature of the encoulastnter itself, but may be determined randomly.
- If creature / NPC reaction isn't obvious, make a **Reaction Roll** (2d6, possibly modified based on what the creature / NPC believes about the party beforehand).
- If someone tries to communicate, make a 2nd reaction roll, this time modified by the speaker's [CHA modifier](#ability-modifier-table) and a modifier based on the first roll as indicated below.
| 2d6 | Result | 2nd Roll Mod |
| :-: | :---------: | :----------: |
| 2- | Attack! | -3 |
| 3 | Hateful | -2 |
| 4 | Leery | -1 |
| 5 | Rude | -1 |
| 6 | Aloof | 0 |
| 7 | Uncertain | 0 |
| 8 | Confused | 0 |
| 9 | Indifferent | +1 |
| 10 | Cordial | +1 |
| 11 | Amiable | +2 |
| 12+ | Friendly! | +3 |
[Reaction Table]
5. **End Turn**: Once the encounter has played out, the turn ends.
- Each encounter is assumed to take at least one full turn to complete.
- This includes time to regroup, bind wounds, clean weapons, etc.
#### Typical Actions
While any action is possible, the following actions are the most common:
- **Combat**: If a side attacks, casts a spell, or makes a tactical movement, [combat](./combat.html) begins.
- **Evasion**: If a side decides to flee, another side may decide to pursue.
- **Talk**: One side may attempt to communicate with the other(s).
#### Evasion
Any side that wishes to avoid an encounter may attempt to flee.
- When on foot, only possible before combat begins.
- In other circumstances (ex: when mounted or on a vessel), may be attempted by declaring intention _before_ the start of a combat round.
- Each opposing side declares whether or not they want to pursue.
- Players decide freely if they wish to pursue fleeing creatures.
- GM decides whether creatures pursue fleeing PCs (based on circumstances or roll).
- If all opposing sides decide not to pursue, the evasion attempt automatically succeeds and the encounter is avoided.
- If an opposing side decides to pursue, the chance of evading depends on the surrounding environment.
##### Party Position
When rolling for an evasion or pursuit, only roll for the parties position: as the evader or pursuer.
- One of the PCs should make an appropriate skilled ability check (typically DEX), modified by their opposition's relative speed.
- Determine results appropriately to the situation.
### Advancement
As the adventures continue, the PCs will interact with their world, gaining Level Points for each session.
- Once a PC acquires a number of Level Points equal to their next desired level, they may gain a level in their desired class.
#### Upon Gaining a Level
When a PC increases their level, the following actions may be performed:
- Roll a hit die (based on the class), and add it to their maximum hit points.
- 1s and 2s may be re-rolled a single time.
- Check the [Skilled Ability Check Modifier table](#skilled-ability-checks) to determine if their skill modifier increases.
- Check the PC's [class](/classes/) and [race](/races/) to see if they gain any new.
- The player may pick one of the PC's abilities, and roll 3d6.
- If the resulting roll is higher than the ability score, increase the score by 1.
### Creature Conditions
#### Blinded
- A blinded creature:
- can’t see,
- automatically fails any ability check that requires sight, and
- only hits on a natural 20 (as a critical hit).
- +4 to attacks against a blinded creature.
#### Deafened
- A deafened creature:
- can’t hear, and
- automatically fails any ability check that requires hearing.
- +2 to attacks against a deafened creature.
#### Entangled
- An entangled creature:
- is unable to move,
- has [disadvantage](./basics.html#advantage-and-disadvantage) on attack rolls and ability checks that require moving,
- can make a new **Save** attempt each combat round,
- is automatically released if the entangling weapon is used to attack another opponent.
- Attack rolls against an entangled creature have [advantage](./basics.html#advantage-and-disadvantage).
#### Exhausted
- An exhausted creature:
- gets -1 to _all_ rolls, and
- has their AC reduced by 1.
- These effects are cumulative for each level of exhaustion they have.
- Each level of exhaustion can be cleared by resting for 4 hours (1 watch).
- Going for more than one day with a long rest adds 1 level of exhaustion per day since last long rest.
#### Frightened
- A frightened creature:
- is unable to willingly move closer to the source of its fear (desiring only to flee from it), and
- has disadvantage on ability checks and attack rolls while it can see the source of its fear.
- Most unintelligent creatures will actively flee when frightened.
#### Invisible
- An invisible creature:
- can't be seen without magic or a special sense (ex: [Truesight](#truesight)),
- can only be tracked by any noise it makes or tracks it leaves, and
- gets advantage on attacks.
- Attacks against an invisible creature have disadvantage and can only be made when attacking creature has _some_ idea of where the invisible creature is (or recently was).
#### Paralyzed
- A paralyzed creature:
- is unable to speak, move, attack, or take any actions; and
- automatically fails any ability check that requires movement or speech.
- Attack rolls against a paralyzed creature have advantage.
- If the attacker is within 5 feet, any attack that hits is a [critical hit](./combat.html#critical-hits).
- Optionally, the GM may rule that a paralyzed creature can be instantly killed (ex: slitting its throat).
#### Petrified
- A petrified creature:
- is transformed, along with any nonmagical object it is wearing or carrying, into a solid inanimate substance (usually stone);
- is unable to speak, move, attack, or take any actions;
- automatically fails any ability check that requires movement or speech;
- ceases to age;
- weighs 10x their normal weight;
- only takes 1/2 damage from everything except explosives and pick-type weapons; and
- is immune to poison and disease (although a poison or disease already in its system is suspended, not neutralized).
- Attack rolls against a petrified creature have advantage.
- When attacked and the attacker fumbles, their weapon breaks.
#### Poisoned
A poisoned creature has disadvantage on attack rolls and ability checks.
#### Prone
- A prone creature:
- moves at half normal speed,
- can stand up for half its normal speed (ending the condition), and
- has disadvantage on attack rolls.
- When attacking a prone creature:
- melee attacks have advantage, and
- ranged attacks have disadvantage.
#### Restrained
- A restrained creature:
- is unable to move, and
- has disadvantage on attack rolls and ability checks that require moving.
- Attack rolls against a restrained creature have advantage.
#### Stunned
- A stunned creature:
- is unable to move, attack, take any actions, and can speak only falteringly; and
- automatically fails any ability check that requires movement.
- Attack rolls against an stunned creature have advantage.
#### Unconscious
- An unconscious creature:
- is unable to speak, move, attack, or take any actions;
- automatically fails any ability check that requires movement or speech; and
- is unaware of their surroundings.
- When a creature is rendered unconscious, they drop whatever they are holding and fall prone.
- Attack rolls against an unconscious creature have advantage.
- If the attacker is within 5 feet, any attack that hits is a [critical hit](./combat.html#critical-hits).
- Optionally, the GM may rule that a paralyzed creature can be instantly killed (ex: slitting its throat).
### Encumbrance
Characters can carry a number of "Important Items", based on their Strength (STR).
- Items can be carried **At Ready** or **Packed**.
- "At Ready" items may be grabbed and used without delay.
- Packing or unpacking items takes 1 turn.
- Characters can carry a number of at-ready items up to their Strength (STR), with a minimum of 7.
- Additionally, characters may carry a number of packed items up to their Strength (STR), also with a minimum of 7.
- Leather armor (with or without studs) counts as 1 item, chain mail and half plate each count as 2 items, and full plate counts as 3 items.
- 2-handed weapons count as 2 items.
- 100 coins or gems count as 1 item.
- Carrying more ready or packed items than allowed can be done, but movement is halved (or worse).
- Carrying more than twice the allowed number of ready or packed items reduces movement to 0.
#### Carrying Capacity
When needed, a character's total carrying capacity can be determined by their [size](#size) and Strength (STR)
- A small or medium character can carry up to 15 lbs for each point of Strength (STR).
- For large characters or bigger, double that capacity for each size above Medium.
- For tiny characters, divide that capacity by 2.
- A character can drag, push, or lift up to twice their carrying capacity.
### Health, Damage and Dying
The state of a character's health is determined by their number of hit points (HP).
- Starting HP is usually determined by class and level.
- The type of Hit Dice to throw is determined by class
- The number of Hit Dice to throw is determined by level.
- Re-roll any 1s or 2s.
- Modify the rolled value of each die by CON as below:
| CON | Mod |
| :---: | :-: |
| 3 | -3 |
| 4-5 | -2 |
| 6-8 | -1 |
| 9-12 | +0 |
| 13-15 | +1 |
| 16-17 | +2 |
| 18+ | +3 |
[Constitution Modifier]
- When damage is taken, HP is lost.
#### Dying
- Creatures and NPCs usually die at 0 HP.
- When a PC drops below 0 HP, they are momentarily [stunned](#stunned) until they **Save** at the end of their next initiative turn.
- The Saving throw is modified as follows:
- the PC's CON modifier is applied to it,
- -1 for each HP bellow 0, and
- +1/2 current level (round up).
- On a success, the PC stabilizes at 0 HP.
- On a fail, the PC can give some potential final words before falling [unconscious](#unconscious), apparently dead.
- While a PC is stabilized at 0 HP, they:
- can only move 1/2 their normal rate,
- can't attack or cast spells, and
- can make an INT check and try to restore their mobility.
- The check counts as a combat action.
- On a full success, the PC heals to 1 HP and can move and attack as normal.
- On a complicated success, the PC remains at 0 HP.
- On a failure, the PC drops to -1 HP and is momentarily [stunned](#stunned) until they **Save** at the end of their next initiative turn.
- Any _other_ character may make an [INT check](#ability-checks) to try and help a stabilized or stunned PC at or below 0 HP, restoring their mobility.
- The check counts as a combat action.
- On a success, the PC heals to 1 HP and can move and attack as normal.
- On a normal failure, the PC remains at current HP.
- On a critical failure, the PC loses 1 HP and is momentarily [stunned](#stunned) until they **Save** at the end of their next initiative turn.
##### Recovering the Body
If the body of an apparently dead PC is recovered, the PC gets one final chance to **Save** or Die.
- Add CON modifier to roll,
- On a success, the PC sits upright wheezing deeply, having only been winded or wounded, and is restored to 1 HP (able to move and attack as normal).
- On a failure, the PC is well and truly dead - there's nothing to do but go through their pockets for loose change.
#### Healing
- After each long rest (8+ hours of sleep), regain 1 _hit die (HD)_ worth of HP.
- Once per day, take a short rest (10 minutes) and eat a ration to regain 1 HD worth of HP.
- Drinking certain potions can restore HP:
- A potion of healing restores up to 1d6+1 HP.
- A potion of greater healing restores up to 2d6+2 HP.
- A potion of supreme healing restores up to 3d8+3 HP.
- Quaffing a readied potion takes a combat action, but can be done while moving.
### Languages
- Anyone who speaks a language can understand other related languages (ex: dialects) with a successful INT check.
- Some orders and guilds (especially those that engage in illegal / immoral acts) may teach their members secret or otherwise coded language.
- The following lists of languages are not all-inclusive.
#### Alignment Languages
Assumed to shared by all (intelligent) members of a given alignment.
- **Chaotic**: Alignment language of chaos.
- **Lawful**: Alignment language of law.
- **Neutral**: Alignment language of neutrality.
#### Class Languages
Most class languages are secret, known only to members of their class, and often include coded terms and/or physical motions (hand waves, knocks, etc.).
- **Assassin's Cant**: Secret (and coded) language known to all thieves.
- Dialects are based on different guilds.
- **Corsair's Cant**: Secret (and coded) language spoken by all Corsairs.
- Dialects are based on different ship / locations.
- **Druidic**: Secret language spoken by all Druids.
- **Thieves' Cant**: Secret (and coded) language known to all thieves.
- Dialects are based on different guilds.
#### Racial Languages
- **Aerian**: Native language of air elementals, dialect of elemental.
- **Angelic**: Native language of angels (law elements), dialect of both lawful and elemental.
- **Aquon**: Native language of water elementals, dialect of elemental.
- **Chitter**: The secret language of burrowing mammals, known to many gnomes.
- **Demonic**: Native language of demons (chaos elements), dialect of both chaotic and elemental.
- **Doppleganger**: Native language of dopplegangers.
- **Draconic**: Native language of most intelligent reptilian races (kobolds, troglodytes, lizardfolk, dragons, dracokin, etc.).
- **Duncommon**: Native language of those that dwell deep underground and other dark places (Drow, Medusa, etc.).
- **Dwarfish**: Native language of dwarves.
- **Elemental**: Spoken by all elementals, each subtype has their own dialect.
- **Elvish**: Native language of elves, dialect of faerie.
- **Faerie**: Native language of the fae, usually divided into 2 dialects:
- **High Faerie** Spoken in the ruling courts of the Faewolde.
- **Low Faerie**: Spoken everywhere outside of the ruling courts of the Faewolde.
- **Farspeak**: Language of the far realms.
- **Firbish**: Native language of firbolgs.
- **Giant**: Native language of giants.
- **Goblinoid**: Native language of most intelligent goblinoid races (boggarts, bugbears, goblins, hobgoblins, etc.)
- **Gnollish**: Native language of gnolls and jakkra.
- **Gnomish**: Native language of gnomes.
- **Greyok**: Native language of several intelligent mammalian animalkin races (Elekin, Hippokin, Rhinokin, Taurokin).
- **Halfling**: Native language of halflings.
- **Orcish**: Native language of ogres and orcs.
- **Pyrean**: Native language of fire elementals, dialect of elemental.
- **Strallan**: Native language of the Stral and official language of the Stral Empire.
- **Terrun**: Native language of earth elementals, dialect of elemental.
| INT | Spoken Languages | Read? |
| :---: | :--------------: | :---: |
| 3 | Native (broken) | No |
| 4-5 | Native | No |
| 6-8 | Native | Basic |
| 9-12 | Native | Yes |
| 13-15 | Native + 1 | Yes |
| 16-17 | Native + 2 | Yes |
| 18+ | Native + 3 | Yes |
[Languages Known]
### Perception Checks
Generally, perception can be checked by making either an [INT or WIS check](#ability-checks).
### Size
A creature's size is usually defined by one of the following categories based on its height and/or weight:
| Size | Max Height | Max Weight | Control Radius |
| :--------: | :--------: | :----------: | :------------: |
| Diminutive | 1' | 1 lb | 1' |
| Tiny | 2' | 8 lbs | 2.5' |
| Small | 4' | 60 lbs | 5' |
| Medium | 8' | 500 lbs | 5' |
| Large | 16' | 4000 lbs | 10' |
| Huge | 32' | 32,000 lbs | 15' |
| Gargantuan | 64' | 250,000 lbs | 20' |
| Colossal | 65'+ | 250,001+ lbs | 30' |
[Creature Sizes]
### Time
Time is often represented at different scales:
- A combat round is 10 seconds long.
- An exploration turn takes 10 minutes.
- A watch takes 4 hours.
- A long rest takes 8 hours.
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