when does an ally burn in combat when playing cards "as a vampire"

My local playing group had a discussion about allies playing cards "as a vampire". I tried to search for an answer, but could not find an clear answer (might be lacking in search fu, so apologies if this has been asked and answered before).

When does a ally burn when playing cards "as a vampire"that require as much blood as his current life?

For example:
Mortal ally is recruited,and is "Ghouled", so the ally can play a basic potence strike once each combat.
Let's say the ally has 2 lifes, enters combat and wants to play Decapitate at basic potence for +2 hand damage(which costs 2 blood).
Is the ally burned immedately, ending combat (strikes don't resolve, opposing minion suffers no damage from the decapitate)?
Or does de strike resolve, the opposing minion gets damage (if undodged/unprevented), and the ally is burned after strike resolution?

I found a ruling that says:
"An ally that plays a card "as a vampire" is treated "as a vampire" for all puposes of the resolution of the play of that card including any continuing effects, but not for effects the card generates for being in play."
This suggests that the ally lives long enough to damage the opponent.

Or is this overruled by the rulebook rule: "An ally or retainer that has zero life counters is burned."?

Thanks!

Thanks for moving it, that was indeed the forum I thought I had posted the question in. Sorry for the inconvenience.

The way I've always thought it worked is that if an ally is reduced to zero life it is immediately burned, but IANPB.

When the minion pays the cost it has 0 life and dies immediately ending the combat.

Okay, thanks! That's how we'll play it, then.