tyranitar pokemon card (222/193) – PokeGuard Colorless Bedrock Breaker (120) Discard a Stadium in play Tyranitar (Triumphant Light #41/96, 3-Diamonds)

As blue is also the color most associated with card draw, even if the top card of your library isn't a Merfolk, you can reliably ensure castable spells are atop your library through the use of card drawing effects and scrying

Sanguinary Priest is a unique take on the Blood Artist effect that can also deal damage to creatures and planeswalkers with the Blood Chalice ability

And even if you don't go crazy, sac a bunch of tokens, get a bunch of Blood Artist triggers, and what have you, you can still easily end up with a pretty big flyer for four mana or give/proliferate it counters through other means

Each individual case can fit 100 double-sleeved card decks easily