Arrin, Hellpit Champion

Whenever you cast a creature spell, you may
discard a card. If you do, draw a card.
{b}{r}, Exile a card from any graveyard: Arrin,
Hellpit Champion deals X damage to
another target creature or planeswalker, where X
is that spell's mana value.
Assimilate 3 (If a source would deal damage to you
or another permanent you control, you may have up to
3 of that damage be dealt to this creature
instead.)