Krox, God of the Shadow

Creatures black or blue you control gets
+2/+2 and indestructible as long as Krox,
God of the Shadows remain on the battelfield. When this creature die or is exiled, you may pay {x} life. This creature return to the battelfield with {x} power and toughness and gains indestructible.
-"Death is independent of everything."