The Omnitrix

If your commander is on the battlefield, you may play
The Omnitrix without paying its mana cost.

—
Alien spells cost {2} less to cast.

Every time an alien enters the battlefield under your control, put a charge counter on the Omnitrix.

Remove ten charge counters: Destroy target creature
then return it to the battlefield under your control.
It becomes an alien in addition to its other types.