The main thing from Mechanics is at the end: Theres going to be ten different Companions, cards that can exist outside of the game and can be cast from the Command zone as long as a condition is satisfied
Birgi, God of Storytelling is busted, Halvar, God of Battle is perfect for equipment decks, and Tergrid, God of Fright is on the Commander Game Changers list
Kuja, Mage Manufacturer Mostly just a 4/5 for tough colors, though I suppose if you have the nut wizard deck, Inalla, Archmage Ritualist could kill pretty fast
Blightsteel Colossus 8.5 For cards that can one shot people this is probably the best
Its a big deal for Constructed more than Eternal formats, but certain Commander decks will welcome another 5-color fixer
Dragonlord Atarka does it all by interacting with creatures and planeswalkers and giving the deck a much needed flyer both for blocking and as an evasive angle of attack