As brought up in the BGG forums:
With AoE effects that do enough damage (such as Oxygen Leak) you could have a situation where the Relic Spirit and Runes of Malediction keep dying and bringing back the other in turn, creating an infinite loop.
How should this be resolved?
Given that the normal method of avoiding loops has been putting a "the first time" restriction, I'm tempted to just say that Runes of Malediction should be errataed to say "The first time each turn Runes of Malediction is destroyed". It would be nice to have a general rule on breaking loops though.
I’m pretty sure in this case you would have the effect deal it’s damage then the reaction effects would take place after the damage has been dealt so the end result would be they just bring each other back after being hit, no infinite loop.
Well, this certainly seems like an issue. I have no good way around it. Perhaps we can hope for an official response on this one. This is the only infinite loop I've seen so far, if that's any consolation. (I think.)
Nah, there's another one I know of. Experimental Mutagen and a sufficiently buff-ed Expatriette with Hair-Trigger Reflexes. The Rat comes in, gets killed, goes back to the discard, and Experimental Mutagen continues bringing rats from the discard. As stated above, the "first time" or "once" solution has usually been suggested to solve this (i.e. Experimental Mutagen brings all rats back "once").
Before it was an oddity, but when you combine this particular loop with Akash'bhuta.....*shudder*.
The experimental mutagen is the same as the Matriarch bringing fowl back from the trash. In that case the ruling was that first everything currently in the trash is pulled out, then put into play. Otherwise just unbuffed 'Hairtrigger' and 'Darken the Skies' are a loop.
The issue with Apostate is that the 'all' isn't on things in the trash, but on the things in play, and in other cases (mainly End of Days) it has been ruled that affecting all in play includes things that enter play while you are resolving it.
Edit: also Hairtrigger Reflexes is optional, so any loop that included it would just continue until the player let it end.