Ravener

Two mechanics that rarely share a card are stapled together here, and the interaction is the entire design. Ravenous scales the body to whatever mana you can dump into X, but the enters-the-battlefield trigger ignores its own stats entirely: it forces a chosen creature to attack a chosen opponent this turn, and it does so at flash speed. That last detail is where the card earns its keep. Cast on an opponent's turn or in response to a combat decision, it can pull a blocker out of position, break up a stalled board, or point one player's creature at another while you sit clear of the fallout. The counters and the goad-style compulsion pull in opposite strategic directions: pour mana into X and you get a threatening flash blocker that draws a card when X is five or more; cast it for its floor with X at zero and you still have a 0/0 that dies immediately but resolves its trigger on the way out, redirecting combat regardless of how big the Tyranid arrives. Most Ravenous creatures ask you to choose between a small early play and a large late one. This one adds a second axis, because the value of the enters trigger is independent of the value of the body, and flash lets you decide which of the two you are buying at the moment it matters most.