Ultra-Bastard D&D: Basic Mechanics

Santiago Caruso

When you attempt a challenging action the DM might require a roll to determine if you succeed. There are two main types of rolls: Ability Checks and Moves.

Ability Checks: Roll d20 + relevant ability modifier vs. a target number set by the DM. If your roll is equal to or higher than the number you succeed.

• If you are playing with the optional Skills rule, you might add a modifier for a relevant skill.
• An attack roll is an ability check made to hit an enemy in combat. These are often made with additional modifiers. Typically, the target number is your opponents armor class.

Moves Roll 2d6 + relevant modifier (specified in the Move's description). On a roll of 10+ you succeed fully, on 7-9 you succeed but incur a complication, and on a 6 or less you fail and the situation gets worse.

• These are especially common in social situations and when gathering information.

Saving Throws: Some hazards and attacks let you make a roll to avoid or mitigate damage. Roll a d20 equal to or UNDER your a target number. The most common saving throws are Armor Class, Spell Save and Ability Saves.

• For armor class saves, roll under 8 + a modifier determined by the armor you are wearing.
• For spell saves roll under a target number determined by the DM + your spell save modifier.
• i.e. the DM might ask you to roll under 5 + your spell save modifier to see if you resist a polymorph spell.
• For most characters, your spell save modifier starts at zero but class features and level advancements might change this.
• For ability saves roll under a target number determined by the DM + your ability modifier
• i.e. the DM might ask you to roll under 10 + your constitution modifier to determine if you succumb to poison.

Special Rules: These are semi-optional.

Advantage/Disadvantage:  When a player has advantage on a d20 role, the player rolls twice and takes the better result. On a 2d6 roll, the player rolls three dice and takes the best two. Disadvantage is the inverse (roll an extra dice and take the worst).

Critical Hits/Fumbles: On a d20 role, a 20 on the dice is a critical hit and a 1 is a fumble. Sometimes, a player may be able to score a critical hit another way (for example, by using Inspiration) or have the range of critical hits or fumbles expanded (i.e. a critical hit on a roll of 19 or 20).

• For attack rolls, rolling a critical hit does maximum damage (count each dice as it's highest number). 

Inspiration: Players can expend inspiration points to re-roll a die or to upgrade a success (from a hit to a critical hit or from a partial success to a total success).