Just look at Niv-Mizzed, Guildpact, a five-mana five-colour 6/6 with Flying and Hexproof from multicoloured that lets you deal damage, draw cards and gain life if youve got colour pairs among your permanents
If you have common or uncommon cards, I would save your energy
There are so many green cards that help make extra mana, find lands from your deck to put them into play, or turn your creatures into lands, or do something else that somehow produces mana, that it's simply impossible to list them all
Marcy: I don't like this as much as the other Emrakul's, but this is still pretty good
An undisclosed but limited quantity was given away during D23, and now some of them are popping up on eBay and other online auctioning sites asking for the kinds of money that already established trading card games, such as Magic: The Gathering and the Pokmon TCG