3e GM rules

This page is for rules that the DM must know but that aren't essential for players. Players are still welcome to read them, however.

Rounding
Whenever a calculation results in a fraction, you always round down.

Effect durations
Effects with a set duration always end at the start of the turn of the creature who caused the effect. Effects with a duration of one round end at the start of the caster’s next turn, those with a duration of two end at the start of the turn after that, etc.

Environmental hazards
Below are a few common environmental hazards, and how they're resolved.

Falling
A fall of 5 metres deals 2d6 damage. Every additional 5 metres increases the damage by another 2d6. Before rolling damage, you can make an agility check. For every 10 points you score with that check, the distance fallen is treated as 5 metres less than it really is.

Fire
If you walk through mundane fire or start your turn standing in mundane fire, you take d6 fire damage. If you catch on fire yourself, you take d6 fire damage, ignoring DR, at the end of each of your turns until you spend an action to extinguish the fire. For simplicity, creatures only catch on fire from special circumstances, such as being covered in oil and lit, never from exposure to normal fire.