Shoot the Hostage: After Argath's defection to Zaalbag's knights, he shoots and kills Delita's sister before shooting Golagros/Gragoroth at Zeakden Fortress
It might not always win a game, but it can push damage through and set up graveyards for you to reap rewards
It hits for 18 damage in a 4-player game on its own, and any sort of on-combat benefits really push it over the top
Jace, Architect of Thought The tutor effect on Jace, Architect of Thought is locked behind a -8 loyalty ability, so its not happening often
Its the kind of effect that gets way better when you have it on demand, since it can easily adapt to a range of different board states
Elesh Norn's second and third ability each affects a permanent's own enters-the-battlefield triggered abilities as well as other triggered abilities that trigger when that permanent enters the battlefield