Rules FAQ

• A character killed for claim is not considered to have been killed by a card effect. That includes normal claim, card effects that instruct a player to apply or satisfy claim (Trial by Combat, Vengeance for Elia, Maester Aemon (WotW), Now It Comes To War, Corn, Corn, Corn), as well as replacement effects that replace normal claim with a kill effect (The Seastone Chair, Mirri Maz Duur). (Source.)