Fogwalker + Quietus Spike
Fogwalker is pretty cheap so it's tossed out early, and its skulk ability makes it so that only creatures with one power can block it. While it's not completely unblockable it usually is, meaning you're usually halving your opponents life every turn with Quietus Spike. The nice thing is, if anything blocks Fogwalker while Quietus Spike is equipped, 1 damage isn't enough to kill it, and whatever blocked you dies. Unless your opponent has a 1 power deathtouch, Fogwalker isn't dieing.
Serpent of Yawning Depths + Spawning Kraken
While both cards combo with (almost) every creature in this deck, the two together is incredibly ridiculous. Creating a 9/9 every combat with Spawning Kraken that is made unblockable by Serpent of Yawning Depths means that unless your opponent is playing a sea creature deck, you have a new 9/9 unblockable every turn
Nemesis of Reason + Sol Ring
Nemesis of Reason is easily the most powerful card in this deck. Making the opponent mill ten on attack means that on a maximum, it will take 6 turns to win (Provided your opponent doesn't have a self-mill deck). The only drawback is that it's a expensive drop, but with a single Sol Ring you can play it on turn 3, and having this card out early means that your opponent is going to lose a lot of cards when they might still be in earlygame
