Selendra, Light Abandoned

{w}{w} {ut}: Choose a party an put a shield counter on each of those creatures. (To choose a party, choose up to one each of Cleric, Rogue, Warrior, and Wizard.)
{b}{b} Monstrosity (If this creature isn't monstrous, it becomes monstrous.)
As long as Selendra, Light Abandoned is monstrous, whenever a creature would die, exile that creature instead and put two +1/+1 counters
on Selendra, Light Abandoned.