Karrthus

Karrthus, called the "Tyrant of Jund", is a dragon Ajani Goldmane encountered on his first planeswalk. Shortly after their encounter, Sarkhan Vol fooled him into thinking that Ajani was his kill in order to spare the leonin's life.

Later, Nicol Bolas captured Karrthus, along with four other smaller dragons, mindwiped them all and brainwashed them into serving Sarkhan and him. He then handed the dragons over to Sarkhan for the battle against Naya and the wresting of the Obelisk of Naya.

In-game references
Represented in:
 * Karrthus, Tyrant of Jund