Whether the advantage is giving you two types of mana (like the A/B/U and Revised DUAL LANDS) or an ability to untap an attacking target creature like MAZE OF ITH from The Dark, these types of cards can turn a simple deck into something powerful and fun to play
For those unfamiliar with the decks interactions, Goryos Vengeance instant card type allows you to reanimate Emrakul from your graveyard while Emrakuls shuffle trigger is on the stack, giving you a hasty 15/15 flying attacker with annihilate 6
What set is Park Heights Pegasus from
Omnath, Locus of Mana While there are certainly more focused commanders, Omnath, Locus of Mana can be generally good for any green deck
(Did you know that Rise of ExtusRise of Extus is the only hybrid card in the game that can go get a card from outside the game?) Avatar: The Last Airbender brought us quite a few mechanics, but sprinkled in with it was an old one that's always been a bit underloved in Commander: Lessons