Lands are often overlooked in many strategies, but as the lifeblood of the game, it can be a tremendous help to bring lands back from the graveyard
This five-mana red and white planeswalker comes in with four loyalty, can create 3/2 spirit tokens, allows you to Discover with a value of four - which means you can cast the next nonland card in your library with a mana value of four or less for free - and lets you exile cards from your graveyard to gain mana, then cast those cards if you want to
Lier, Disciple of the Drowned Anti-Control Control Lier, Disciple of the Drowned is one of the more interesting blue commanders Ive seen in a long time
Heliod, the Radiant Dawn is a very straightforward commander in this way, costing a fairly cheap four mana to transform him, or three mana and two life, to compleat the poor god, turning him into a twisted, Phyrexianized version of himself
Dredge decks effectively empty their entire libraries into their graveyards, then take their pick of powerful effects