4 color mtg cards Omnath, Locus of All Activated abilities of artifacts your opponents control cant be activated 3 Decks to Beat Four-Color

Also, even if you cannot remove all creatures, reducing their numbers makes it easier for Xande to get through

(6/7/2024) To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as an escape cost), add any cost increases, then apply any cost reductions

If that wasn't enough, if you cast a spell which is multiple of these MTG colors, you get each of the abilities that share a color with the card cast

At four mana, he can sit at the top of your mana curve, and if you manage to drop a haste enabler such as Goblin Warchief, you can start doubling your goblins straight away (which then also have haste to attack the turn they enter)