So in Civil War there was a wave node with Jean Grey in the first wave. When she was killed and replaced with 3 fresh new characters she still left her phoenix countdown tile.
Sadly (or thankfully depending on the outcome) Vulture removed that countdown tile for me.
What would happen if it had reached 0? Nothing? Replacing one of the other character? 4 characters on one side? Crash?
According to some reports in the Bugs forum, it brought someone else back sometimes.
Nothing happened. I let the countdown finished.
I had to use Gambit in all of the nodes to overcome the crazy scaling, so her countdown tile always got overwritten by his Purple.
Your device bursts into flames and you become the new Phoenix IRL.
Thanks for the morning laugh 
Weird, I’m not playing on a Samsung.
I filed a report in the Bugs & Technical Issues forum for this issue. If one character on the second wave is downed when it expires, Phoenix’s countdown tile will bring them back to life at half health. Not sure whether or not that character needs to occupy the same position in the lineup as Phoenix did, though.
It happened to me and IIRC it resurrected Nick Fury in the next wave. Kinda funny really.
I want Nick Fury to be the new Phoenix. “Let’s see those [tinykitties] try to shoot down my helicarrier this time. JUST TRY IT!”
I still think that sounds like a spoiler for Avengers 4 
“Enough is Enough! I’VE HAD IT with these tinykitty snakes on my tinykitty helicarrier!”