Fortunately, Emrakul is banned in Commander, but it can still terrorize the Modern and Legacy formats.
Zidane Tribal Ragavan, Nimble Pilferer can be extremely groan inducing on turn 1, but surprisingly tame in Limited otherwise
Another subtly powerful card to include is Raiders' Karve, a common Vehicle that looks at the top card of your library when you attack, and if it's a land, puts it into play tapped
When Loki puts the token in tapped and attacking, it will miss this
About the deck's core: 'Mana Ramp' The preconstructed deck 'Reap the Tides' is not a bad deck as it is, but the lack of land-based mana ramp, which is crucial, is a painful point