Meglonoth

Most defensive creatures punish the attacker; this one reaches past it to bleed the player who sent it in. The trigger fires when the Beast blocks, dealing six damage straight to the attacking creature's controller on top of the 6/6's combat math, so every creature swung into it costs life whether the attacker lives or dies. That inverts the usual incentive structure of a wall: the body already eats most ground attackers, but the controller-damage clause means trading a bigger creature against it, or sending in something just to absorb a turn, still ships damage upstairs. Vigilance compounds the trap, letting the body threaten lethal on the swing and still stand back to collect on the block, collapsing the attack-or-defend tension a six-mana fatty usually has to navigate. The damage scales off power rather than a fixed number, which keeps the two halves locked together: pump effects raise both the swing and the block tax at once, and any power reduction defangs both. It is built squarely for the Naya identity of big, aggressive midrange creatures, where a beater that also taxes the opponent for engaging it fits the shard's whole thesis of making every combat step expensive for the other side. The trample-and-vigilance shell is conventional; the controller-damaging block trigger is the part that gives the card teeth no plain ground-pounder of this size has.