Omnath, Locus of All {W}{U}{B/P}{R}{G}
Legendary Creature — Phyrexian Elemental
Identity
Five-color
EDHREC rank
#5,495
Cheapest printing
US$0.43
TCGplayer
Printings
5
If you would lose unspent mana, that mana becomes black instead.
At the beginning of your first main phase, look at the top card of your library. You may reveal that card if it has three or more colored mana symbols in its mana cost. If you do, add three mana in any combination of its colors and put it into your hand. If you don't reveal it, put it into your hand.
Every printing
highest TCGplayer market first; a card with only a thin single listing shows its low
In short
A Commander deck is a commander and 99 other cards, one copy of each (except basic lands), all inside the commander's colour identity. Paste a full list into the deck price calculator to price it and check it against the format.