Even though your turn ends as soon as you play it, Mega Charizard has 230 HP so it can take some damage
This makes them incredibly flexible, as you can either cast the front face and transform it later, or straight-up cast the back face later in the game
You can search for Kwain, and then scroll down to see all the top cards used in decks that run it as a Commander, like Dictate of Kruphix, Teferi's Ageless Insight, Kami of the Crescent Moon, and Laboratory Maniac
I'll come back with updated designs and hopefully new ones, once I had some time to think about it
Aminatou, the Fateshifter Commodore Guff Daretti, Scrap Savant Dihada, Binder of Wills Elminster Estrid, the Masked Freyalise, Llanowar's Fury Jared Carthalion Jeska, Thrice Reborn Lord Windgrace Minsc & Boo, Timeless Heroes Nahiri, the Lithomancer Ob Nixilis of the Black Oath Quintorius, History Chaser Rowan Kenrith Saheeli, the Gifted Shorikai, Genesis Engine Sivitri, Dragon Master Tasha, the Witch Queen Teferi, Temporal Archmage Tevesh Szat, Doom of Fools The Grand Calcutron Will Kenrith