Ancient Cornucopia's triggered ability counts the number of colors the spell has (from one to five), not how many colored mana symbols there are in its mana cost or how many colors of mana you spent
And note that the last ability triggers on opposing artifacts going to the graveyard, too
She sucks up three more trample damage as well
Decks that rely on fast mana, like combo decks, can go as low as 14 lands, as they make use of mana rocks like Lotus Petal or cards like Dark Ritual to add mana and cast as many spells as they can to execute their combo
With the myriad of purple support, especially those with the Straw Hat trait that directly benefit the deck, this deck has consistently been at the top of the meta for a while
Creatures (7) Lands (23) Spells (30) 4 Hymn to Tourach 2 Yawgmoth's Will 4 Duress 2 Firestorm 4 Necropotence 4 Dark Ritual 4 Drain Life 3 Contagion 3 Demonic Consultation Sideboard Ive always enjoyed the 2 Yawgmoths Will experience, the true embodiment of discipline