Hanyu, Eternal Guardian

Indestructible, flying.
As long as you have fewer than five experience counters, Hanyu isn't a creature.
{w}{u}{b}{r}{g}: Take an extra turn after this one.
At the end of that turn, you get five experience counters, then you lose X life and exile the top
X cards of your library, where X is the number
of experience counters you have. Activate this
ability only once per turn, only on your turn,
and not during extra turns.