Kerberonyx

Whenever Kerberonyx attacks, exile the top card
of each player's library, then you may cast any
number of spells from among those cards without paying their mana costs.
"Genetically near-identical to Kerberons, but some [CORRUPTED TEXT] seem to cause an individual
to mutate, becoming larger, more damage-resistant and
able to spit a higher amount of projectiles in one
expulsion."