Uroborus, Sire of Hunger

Eminence - Wurm spells you control have: "As
you cast this spell, you may exile a creature you control. If you do, reduce this spell's casting cost
by the casting cost (including color)of the exiled creature. This creature enters play with X+1,
+1/+1 counters, where X equals the number of +1/+1 counters on the exiled creature.
Wurms you control with toughness 6 and greater have vigilance, trample, and reach.