River Serpent

The whole pitch of this design is a delayed-attacker tension: a 5/5 body that arrives inert and stays that way until your graveyard fills to five, paying for its aggressive stats with a clock someone else has to start. The card answers that tension by being two cards at once. Cycling for a single blue turns it into a cantrip the moment the board is wrong for a fat blue beater, and every cycled card, every spell cast and discarded, every land that hits the yard, builds toward the five-card threshold that unlocks a different copy later. The attack restriction is the kind of self-fulfilling cost a controlling deck pays passively; the longer the game runs, the more the restriction erodes, until the body that could not swing early is a genuine finisher in the back half. It is a graveyard payoff wearing the clothes of a plain creature, the soft inverse of a flashback or threshold card: instead of cashing the graveyard in, it waits for the yard to grow large enough to permit combat. Because the floor (a blue draw) and the ceiling (a 5/5 that swings once the yard is stocked) live on the same piece of cardboard, it rarely sits dead in hand; the deck decides which half it needs and takes it.