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.
Omnath turns every leftover mana into black mana and refills your hand each turn while spitting out free colored mana off the top of your library, making it an engine for casting huge multicolored spells across all five colors. You ramp hard, draw a card every main phase, and dump the surplus into big payoffs, multicolor bombs, or a combo finish. The deck snowballs on raw card and mana advantage until you out-resource the table.
Guaranteed extra card every turn that often comes with three free mana
Color-of-mana fixing is irrelevant since unspent mana becomes black and you can run all five colors freely
Excess mana from rituals, rocks, and big lands never goes to waste
Five-color identity means access to the best removal, ramp, and bombs in the format
The reveal payoff rewards heavy multicolor builds, creating tension with consistent mana bases
Card-advantage engine is on the commander, so repeated removal taxes you hard
No built-in protection or evasion; Omnath does nothing the turn it lands
Can be slow and grindy without a focused finisher, durdling into a stalled board
Generates Treasures that feed Omnath's mana retention and accelerate your big turns.
Lean into the multicolor density so the reveal trigger nets free mana more often, then add fast mana like Mana Crypt, Jeweled Lotus, and strong rocks to power explosive turns. Pick a tight win condition—an infinite mana combo with Cascading Cataracts/Codie-style outlets or a reliable X-spell—so you convert your resource lead instead of durdling. Tighten the mana base with fetches, duals, and Triomes, and add protection like Heroic Intervention and Teferi's Protection to defend the engine.
Legendary Creature — Phyrexian Elemental
