Azir, Sand Emperor

When Azir enters the battlefield or attacks, create 3 1/1 Sand Soldier tokens with haste and "Sacrifice this creature at the beginning of your end step"

Whenever a Sand Soldier token dies, put an experience counter on Azir, Sand Emperor. If Azir has 10 or more experience counters, Sand Soldier tokens are 3/3 creatures with haste and double strike.

When Azir, Sand Emperor has 30 experience counters, exile him, then return him to the battlefield transformed.