Soul Eater Shield

Enchant creature with defender.
When Soul Eater Shield enters the battlefield,
return each other Shield enchantment attached
to enchanted creature to its owner's hand.
When enchanted creature blocks, put a mana
counter on Soul Eater Shield.
Enchanted creature has +0/+2 and "{t}, Remove
X mana counters from Soul Eater Shield: add X
mana of any one color."