Hy'dya, the Experiment

Champion a Guardian Planeswalker (When this
enters the battlefield, sacrifice it unless you exile a
Guardian Planeswalker you control. When this leaves
the battlefield, that card returns to the battlefield.)
Immortal (Spells and abilities cannot reduce this
creature's toughness less than 1)
Hy'dya, the Experiment has all the activate
abilities of the championed planeswalker.