Alex Mercer, The Prototype

If a nontoken creature would die, exile that
card with a blood counter on it instead.
As long as an exiled creature card with a blood counter on it has flying, Alex has flying.
The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection,
reach, trample, and vigilance.