It makes removal part of your game plan and that alone is powerful
Tegwyll is a fairly aggressively-costed commander at only three mana and has both flying and deathtouch, making it a deadly creature to contend with
It looks like a very fun card to resolve though
I will say that a split is certainly justifiable, and I would be remiss to not suggest having access to Charm from the board
From humble beginnings playing Ayli, Eternal Pilgrim with some janky-ass combos, to Teysa Karlov, Regna & Krav partners, Nalia deArnise and other precons, both Liesa, Shroud of Dusk and Liesa, Forgotten Archangel (two very different decks), Ive tried many different styles
My issue with this changeling is that it needs something to copy as it enters unless you cast it using snow mana with Boreal Outrider on the battlefield