Many black decks in EDH revolve around treasure synergies or typal synergies, and having this black enchantment around improves both
Number 41 Language English Legal Formats Commander, Legacy, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Modern, Pauper, Pioneer, Standard, Timeless Rulings (8/25/2017) The exiled cards remain exiled with cage counters when Mairsil leaves the battlefield
Ajani, Nacatl Pariah / Ajani, Nacatl Avenger Ajani, Nacatl Pariah is a warrior that can handle itself formidably, but really shines with at least a couple cats in the litter
Cryptic Command would still be a versatile and powerful card even if you always had to chose counterspell as one of the options but if that were the case you go from a card with 6 options to one with 3
Exile your hand to draw a fresh one, but you can still play what you remove until your next turn