Triggering 'When this unit attacks' action

By Pitrix, in Warhammer Invasion Rules Questions

Hi,

Question regarding Wolf Chariot which action says:

Action: When this unit attacks, sacrifice a unit you control. This unit gains [Power] equal to the sacrificed unit's loyalty until the end of the phase.

When exactly do I trigger this action?

Can I trigger it multiple times?

If yes, how does Great Fire Dragon action work?

Action: When this unit attacks, put 1 resource token on it. Then, you may remove X resource tokens from this unit to deal X damage to target unit in the attacked zone.

You trigger it in the action window that happens right after you declare all your attackers. Generally, you can only trigger it once because that unit can only attack once per phase...unless you're playing Cataclysm where there can be 2 attacks in a phase.

Great Fire Dragon would also trigger in this same action window and also generally only once unless you're doing Cataclysm format. Keep in mind with the Dragon however that you are not forced to do the part of the action after the "then" in the text. Over the course of a few turns, you could build up those tokens and use them all up at once on a particularly large and troublesome unit - providing you can keep your Dragon alive long enough...

Juglecat, this makes complete sense.

Thanks a lot for clarifying this. I couldn't find it in the rules or FAQ.