Kiora's Dambreaker

Most creatures that proliferate on entry come as small, fragile bodies, so the trigger has to carry the card by itself. This Leviathan inverts the arrangement: a 5/6 wall for six is a real floor, and the proliferate is a bonus a counters-based midrange deck can lean on without ever depending on it. The body dodges damage and toughness-based removal by sheer bulk, though it stays fully exposed to destroy and exile effects like any other creature; what it buys is a durable blocker that also does something the turn it lands. With nothing on the board carrying a counter, you have simply paid for a large blocker. With a board already invested in them, the entry nudges a planeswalker toward its ultimate, advances a saga a chapter, or thickens a stack of +1/+1 counters. The card never asks you to build around it; it asks only that you have something worth advancing when it arrives, and it pays that off while still holding the ground. That is the cleaner half of the enters-with-proliferate design lineage: the trigger is the reward for a deck already committed to counters, not the reason you are casting the spell.