GM

The Gamemaster decides what happens in the game. If a skill check is needed, the Gamemaster decides what skill should be used. Sometimes the Gamemaster makes the skill check himself, behind his screen, in case the player shouldn't know the result.

Also the Gamemaster decides is a bonus or a penalty is required. A -2 bonus means that the second largest die (d6) is subtracted from the score. A +3 penalty means the third largest die (d8) is added to the score. Also there should be a reason behind each special die, such as, a +3 step penalty (hard to get there), +3 cover penalty (the enemy has cover) or a +3 GM's wrath penalty (if you just feel like it).

Encounters for the GM are roughly the same as what is mentioned in the movement section (except for encounter with a good character)

If a hero is questioning someone, you decide what answers the person gives. You decide everything about this person. You are GM.

In combat, the GM decides what the characters do. Each character has a different personality, and its up to the GM to exploit it. If a character is stealthy, he shouldn't run into the room screaming like a monkey with his head cut off. He should use skills like Sneak. Also the situation die is used greatly in combat too.