Initiative checks.

Initiative checks decide how quickly a combatant realises there is an enemy nearby at the start of combat. Initiative checks are made in the first round of combat, and that initiative score stands for the entire combat.

An initiative check is made by rolling 1d20 and adding the players intelligence bonus. The combat is then resolved in order of who scored the highest, to who scored the lowest.

If a character reaches their turn, and they have an ally with a lower initiative, that character can use their defencive action for that round to do something that might increase the initiative of the ally (such as shout 'enemy'). The target ally must take an intelligence test, and if such a test is passed, the ally will +4 to their initiative score. Note this action can only be made in the first turn of combat (Before the target ally has attacked), and a player can only be targetted by this action once. Also note that regardless of all else, the initiative boost gained in this manner can only ever take the ally up to the initiative score -1 of the person who boosted their initiative.

Example:
Bill and Bob enter combat and make an initiative roll. Bob rolls a score of 18, Bill rolls 15, the enemy rolls 16. Normally the striking order would be Bob, enemy, Bill. In Bobs turn, Bob tries to raise Bill's initiative by calling 'look out!' Bill passes an intelligence test and as such, gains a +4 to initiative. However, Bill's initiative cannot match or exceed Bobs, so Bill only gains +3 initiative, taking him to 17 (1 lower than Bill's.)