Baloth Prime

A 10/10 for four mana is a rate that would break open a game if you could deploy it clean, so the design buries the cost inside the body: six stun counters, which means six untap steps burned removing counters plus a seventh before the creature is legal to attack. The card doesn't ask you to wait out those steps; it asks you to buy them off. Every land you sacrifice both spins off a tapped 4/4 Beast and tries to untap the creature, and while stun counters remain that untap is replaced by removing one instead, so the payment schedule and the reward schedule run on the same lever. This is why the card wants a shell built around sacrificing lands rather than one that stumbles into it: fetchlands, sacrifice-outlet lands, anything that treats a land as a resource to spend turns a dead 10/10 into an engine that unlocks itself and pays out a growing army as it goes. (Note that landcycling won't do the work here; it discards a card from hand rather than sacrificing a land on the battlefield, so it never touches the trigger.) The activated ability that trades a land for two life is nearly incidental next to the sacrifice trigger, but it gives the engine a floor when there's nothing better to do with a spare land. The structural bet is that in a deck already sacrificing lands, six stun counters are not a drawback at all; they're a countdown you were going to sprint through anyway, and each tick leaves a 4/4 behind.