Glissa the Eternal

Undying, haste
Whenever another creature you control attacks, you may remove all counters from it. If you do, it gets +X/+X until end of turn and you add X mana in any combination of colors to your mana pool at the beginning of the next phase, where X is the number of counters removed this way.
Remove a +1/+1 counter from Glissa, Sacrifice another creature: Put a +1/+1 counter on each other creature you control.