How often can an action on a card be taken?

By great177, in Warhammer 40,000: Conquest - Rules Questions

Hello all. I'm new to the game and I've been doing a lot of rules research and I have been able to answer all my questions so far but one.

How often can you take an action on a card? I would assume it's once per phase or turn but I can't find anything to back this up. For example Haemonculus Tormentor has the ability "Action: pay 1 (resource) to give this unit +2 ATK until the end of the phase." Could I pay 2 resources to increase his attack by 4?

You can trigger "Action" abilities as many times as you can meet their play restrictions, pay their costs, etc. So yes, you could pay 2 resources to increase the ATK of Haemonculus Tormentor by 4.

Note, however, that it takes you 2 separate actions to do this. You cannot choose to pay 2 resources to get +4 ATK when you trigger the ability. Rather, since actions trade off between players, you can pay 1 resource for +2 ATK, then your opponent gets the chance to trigger an action, then on your next action, you can pay 1 more resource for another +2 ATK -- bringing the modified ATK to a total of +4. This difference is very important within the timing structure of the game.

Also, remember that you can only trigger an "Interrupt" or "Reaction" ability one time per triggering condition. For example, you cannot commit Eldorath Starbane to a planet, then trigger his Reaction as many times as necessary to exhaust all enemy units at that planet. You only committed him once (the triggering condition), so you can only trigger the Reaction once.