Maiev, Warden Master

Stealth. Counters remain on Maiev as it moves
to any zone other than a player's hand or
library. Put a +1/+1 on Maiev each time it jails a
creature.
When Maiev deals combat damage to a player,
you may exile to jail target creature that player
controls. Then, return creatures from jail to the
battlefield until the total power of jailed creatures
is less than Maiev. When Maiev dies, return all
jailed creatures to the battlefield.