Kelryna Morningdance

Prepare {u}: When a creature enters the battlefield, put a charge counter on Kelryna Morningdance.
When Kelryna Morningdance enters the battlefield, you may put any number of creatures
you own in your hand or exile onto the
battlefield if their combined mana value is equal
to or less than the number of charge counters on Kelryna Morningdance.