In general, the best way to play Xanathar, Guild Kingpin isn't to simply cast as many of our opponent's spells as possible but to play some cards and then try to leave our opponent with a useless card (most often a land) on the top of their deck, which is almost like making our opponent skip their next draw and, if our opponent is empty-handed, pretty close to making our opponent skip their turn
Anthem of Champions is a clean, 2-mana enchantment anthem that will make some noise in these rabbit go-wide decks
That poor huge tumour-moon in Chaos Confetti is clearly distressed as giant human hands are ripping it up
Arcane Signet taps for any color in your commanders identity, so its perfect for multicolor decks that need consistent fixing
Just like the DnD deck it's based on, the card can have a range of effects, some game-winning, other catastrophic
Its hard for your opponents to keep up if they cant resolve spells, and youve got plenty of cantrips like Ponder and Preordain to make sure youve always got the appropriate answer