Multani, Yavimaya's Avatar

The defining move is the second clause of the buff, the one that counts land cards in your graveyard. A creature that scales off lands you control is old design; treating dead lands as live stats is the wrinkle that turns this from a "count your permanents" body into something that gets bigger the longer the game grinds. Every fetch cracked, every land milled, every sacrificed manabase feeds the size, so the effects that normally shrink your board (land destruction, self-mill, fetchland thinning) all hand this an upside they otherwise never carried. The static buff means the body arrives already enormous: the six mana it costs guarantees a wide manabase, and by the time you can cast it the graveyard has usually started filling too. Reach and trample are the practical glue: reach keeps an air force from chipping in over the top of a green giant that already dominates the ground, and trample forces the damage through the chump blockers that a body this size invites. The recursion is the part worth reading carefully, because it cuts against the buff on purpose: returning two lands to hand shrinks the count in play, so the loop trades present size for the chance to replay those lands and rebuild. Every land bounced this way is a future point of graveyard fodder once it dies again, which is the quiet engine here: a creature you can keep killing that comes back a little harder to keep dead each time, feeding on the exact resources most decks try to preserve.