Kabibon, The First Of Wendigo

Whenever a creature you control dies, add {b}{b}{g}{g}. Spend this mana only to cast spells
from under Kabibon, The First Of Wendigo.
Then, you may pay {b}{b}{g}{g}. If you do, exile
that creature under Kabibon, The First Of
Wendigo.
You may cast creature spells from under Kabibon,
The First Of Wendigo. Spells you cast that way
cost {2} more to cast.