Thassa's Emissary

A creature that draws you a card every time it connects is the kind of engine aggressive blue decks rarely get to keep, because the usual answer is a removal spell that takes the whole package to the graveyard. This Crab dodges that math. Played straight, it's a 3/3 that refills your hand every time it lands combat damage. For its six-mana bestow price, it instead rides an existing attacker, hands that creature +3/+3, still draws off its hits, and survives the host's death by falling back into play as its own 3/3 body. That survival clause justifies the premium: the card advantage never rides to the graveyard with the creature it enchanted, so a removal spell aimed at the enlarged attacker only strips the boost and leaves your 3/3 standing rather than answering both halves at once. The trigger's "this creature or enchanted creature" wording isn't handing you two bodies; while bestowed the card is an Aura, not a creature, so the phrasing simply guarantees the draw fires in either of the card's two states, attached or standing on its own. The result is a single blue threat that taxes the opponent twice: ignore it and they feed you cards, kill it and they leave a body behind. Bestow's flexibility is the insurance, letting one card play as a threat, a pump spell, or both depending on how the board is trading.