Verity Circle is the engine that this deck runs on. It's possible to win without using it, but a lot more fun if you do. The idea is to use Unsummon, So Tiny, etc. to stay alive long enough to get it up and running. Ominous Seas is a great way to put the card-drawing power of the Verity Circle engine to work, and this is how you'll eventually spin up enough damage per turn to win the game. Once you have a Verity Circle or two, there are a lot of other combos that take advantage:
Heliod's Punishment is my personal favorite because you get to watch your opponent squirm as they decide whether to give up their creature or to let you have 4 cards (or 8, or more, if you have more Circles) over 4 turns. Even if you don't have the Circle out yet, Heliod's Punishment can probably buy you enough time.
Stinging Lionfish is a criminally underrated card, and this deck really gives Fishy his due. You can juggle a decent number of enemy creatures with a fish or two and a few cheap spells like Unsummon or So Tiny, especially once you get Verity Circle (or Circles--they stack!) and you get to draw with every tap. Fishy by himself will often deter early-game attacks from mana dorks and cheap deathtouch creatures, and can land some quick punches against opponents without early creatures. Most opponents don't perceive Fishy as a big enough threat to warrant a removal spell, and by the time they realize his role in the card-drawing engine, it's usually too late.
Gadwick, the Wizened and Giant Killer synergize really well with Verity Circle. Gadwick's ability drives so many card draws that I usually end up casting him with X = 0 because I'd end up having to discard the cards anyway. A typical mid-to-late game scenario will have you bouncing an enemy creature with Unsummon, tapping a second enemy with Gadwick, tapping a third and fourth with a couple Lionfish, and drawing a total of six cards if you've managed to get two Verity Circles out...all for the cost of one lousy drop of blue mana. If you have Ominous Seas out, those six cards will get you most of the way to a fresh 8/8 Kraken, too.
Clear the Mind proves useful in those really long, knock-down drag-out games because once the Verity Circle engine really gets going, you're probably drawing 5-10 cards per turn. Mystic Sanctuary lets you get Clear the Mind back so you can cycle through the whole deck again if you really need to.
