King Meruem

Eminence — As long as King Meruem is in the
command zone or on the battlefield, other
creatures you control with mutate have hexproof.
Final mutate {4}{u}{b}{r}{g} (Mutate. Creatures can
no longer mutate onto this creature.)
When this creature mutates, put X +1/+1
counters on this creature, where X is the total
power among all creatures that mutated
onto the creature.