Exponential hydra

Level up {4}{g} ({4}{g}: put a level counter on this.
Level up only as a sorcery)
Lvl 0-4 - At the beginning of your 2/2
turn double Exponential Hydra's power
and toughness
Lvl 5-10 - At the beginning of your 4/4
turn quadruple Exponential Hydra's power
and toughness
Lvl 11+ - At the beginning of your 6/6
turn sextuple Exponential Hydra's power
and toughness