Echo

Echo is a keyword ability on permanents that requires the permanent's controller to pay its casting cost during the player's next upkeep after that player gains control of it, or sacrifice it. All tournament-legal cards with echo were printed in Urza Block.

From the Comprehensive Rules:

• 502.19. Echo

• 502.19a Echo is a triggered ability. “Echo” means “At the beginning of your upkeep, if this permanent came under your control since the beginning of your last upkeep, sacrifice it unless you pay its mana cost.”