Riposte

I think I am making a meal trying to understand Fatal Flaw, probably because it might allow two opposed rolls in one action.

Fatal Flaw* vs AP1
May be combined only with a close combat action & Fatal Flaw* deals no damage. If the action was successful, the next friendly combat action against the target model in this round benefits from +3 to the opposed roll.

I cannot figure out how this ability works.

Does it have to be combined with a close combat action or can it be used alone?

If the former which action has to be successful – Fatal flaw or the combat action. If it’s the combat action do you even roll for Fatal Flaw?

If it is used with a combat action can it be used immediately before the action to give the +3 to that action?

I think it’s this:-

Fatal Flaw* vs AP1
The only actions Fatal Flaw may be combined with are close combat actions. Fatal Flaw* deals no damage. If Fatal Flaw* is successful, the next friendly combat action against the target model in this round benefits from +3 to the opposed roll.

Which is so similar you can see how I am being obtuse. I keep reading may as must ...

Team Power: Tactical Insight
Can I make one measurement or as many as I like?

It's the combined action that gets the benefit from fatal flaw...

So, you combine it with a strike. Roll for Fatal Flaw. If successful, the combined strike gains the +3.

Otherwise, if you don't combine it, and Fatal Flaw is successful, the next combat action gains a +3.

You don't "have" to combine it, but if you do, it must be a close combat action.