I'll keep it short and simple. Kayn, Aatrox and Varus are the only Darkin in the game. Kayn has his scythe Rhaast and Aatrox is the sword that's consumed the user. Shouldn't Varus (also change the name to Vaarus) have his ultimate reworked a little? Where he takes on a darkin form and gives him a new set of abilities (For the duration of the ultimate) There's nothing that screams Darkin with Varus really. Kayn talks to Rhaast and Aatrox... well he screams it so.
Instead of that binding crap his ultimate gives him, Varus should have a form change ultimate where be becomes a full on Darkin with a fresh new set of abilities while the ultimate lasts.
Idk what do you think?