Once the first triggered ability is on the stack, it won't trigger again, even if more damage is prevented and more incarnation counters are put onto it
If at least one target is still legal at that time, the spell resolves, but an illegal target cant perform any actions or have any actions performed on it
It's likely to catch removal, but if it sticks you'll have a rapidly growing flier that makes your opponents sacrifice a nonland permanent with every attack
If youre good enough at predicting the Standard metagame and you have the ability to move a lot of cards as soon as you get them in, then you have no reason to cross your fingers on the long haul like Im doing with the above cards
It shows solid intent from the Pokemon Company to usher in the new era in style, and with Phantasmal Flames up next, it's only set to get better
With good reason