Genmu Voidruler- Ballom Star

Mugen Climb 4 (You may cast this spell for {4} less by tapping 4 permanents you control)
Galactic Dragon Evolution (You may cast this spell over a target Galactic Dragon creature you own. They evolve into the creature on top, if the card would leave the field, only the top card leaves the field)
{u}{t}: tap X targeted creatures your opponent controls, where X equals any Mugen Climb value on cards under this.
{b}{b}{ut}: destroy all other untapped nonland permanents on the field, this creature gains has