This ingenious loop turns Karrthus, Tyrant of Jund—a legendary dragon designed to rally your scaley kin—into its own recursive engine once enhanced by Splinter Twin. By enchanting Karrthus with Splinter Twin, you gain the ability to tap him to create a token copy of himself. Because Karrthus is legendary, the state-based legend rule immediately sends the token to your graveyard, but not before its entrance triggers its own ability to untap all dragons you control. This untaps the original Karrthus, allowing you to repeat the process indefinitely for infinite creature entries, exits, and death triggers to overwhelm your opponents.