Cavern of Souls, Path of Ancestry, Unclaimed Territory, and Secluded Courtyard all are lands that benefit decks that focus heavily on a certain creature type
Three Mythics come in as transform cards, Gwen, Miles, and Peter, flipping into their heroic alter-egos on the back
Since Sothera exiles, it prevents those creatures from triggering death triggers, and lets you take a creature for yourself if a battlefield is ever empty
Plus, each copy of the game comes bundled with a Box Topper containing one of Ravnica's famous shock lands
Thanks to the slower nature of Commander, you should have ample time to set the combo up, as well, but it will have a smaller impact on the game thanks to having four opponents
Like Flynn Rider, Charming Rogue above, Cheshire Cat, Not All There is an excellent emerald card to get out early in the game to disrupt your opponents, forcing them into dilemmas that slow them down and ruin their plans