Emrakul, the Aeons Torn [Best Finisher for Closing Games Immediately] Fifteen mana is a steep price, but Emrakul rarely gets cast the fair way
We should emphasize that Too Greedily, Too Deep doesn't specify which graveyard you reanimate from, so you can just as easily swipe a dead creature from your opponent's graveyard to wipe the board with as you can your own
This means if your opponent removes him, you can replay him from the command zone and regain access to all previously stolen cards
Sigil of the Empty Throne
Both are legendary in more than name, with The Masamune giving first strike when attacking and forcing a foe to block, while also giving double triggers for creatures dying
You can keep doing this until you have a large board and then you copy a powerful finisher like Craterhoof Behemoth