Basically, the bigger the cube is, the less likely it is that a player in a given archetype will see the key cards they need
Scryfall Scryfall is one of the easiest places to search for MTG Final Fantasy cards once names and card data are available
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
There are no cards that do not have a drawback in some way, perhaps conceding clues, perhaps lands, perhaps they are gold (XY) or merely colour intense (XX), perhaps they are just sorceries
If you have common or uncommon cards, I would save your energy
Ezuri only costs 3 mana for a tribe that produces mana more easily than any other