Treebeard is an extremely underrated hero. Probably that he has such a good ally version doesn't help (as a rule I have one copy of ally Treebeard in every single deck I build).
But don't be afraid of his high threat, he is worth every point of it due to his amazing ability. Once you load up some Healing and readying on him (which is why he pairs excellently with Elrond hero) he becomes a repeatable rockstar. Throw an Ent Draught on him and he is questing at 7 and hitting for 8 just naturally. Find ways to ready him with Unexpected Courage, Lembas Bread, Cram, Miruvor (huh a lot of food items on this list) and so on and he will single-handedly quest big and win wars for you as a deck centrepiece.
My favourite combos with him are:
-Path of Need, Henmarth riversong and Burning Brand on Treebeard to make him stand firm against all assaults and then obliterate seas of enemies with his non-exhausting 8 attack.
-Fall of Gil-Galad + hero-saving cards (preferably free via vilya) and you have super threat reduction that you can trigger at any time.
-Elrond and any healers or healer cards (Wellinghall Preservers, Warden of Healing, Daughter of the Nimrodel, Self-Preservation, aforementioned Lembas)
He also pairs great with Gloin if you are going the Elrond healer route for some deck madness. Check him out and let Treebeard lead you to victory!