Wendy Carter, The Bereaved

As an additional cost to cast this creature, sacrifice a creature.
When this creature is cast, create a 5/5 white legendary Spirit creature token named Abigail.

Whenever a creature dies, create {b}. This mana can only be used to cast Spirit creatures.

{t}, Sacrifice a creature: All Spirit creatures you control get a +1+1 counter. Put two +1/+1 counters on Abigail.