I see, tablet of completion seems completely useless here you should cut it for the archfiend of despair. So karn is only useful when youre in an artifact heavy playgroup, which im guessing youre in then hahah. Do note that infernal darkness also shuts down your own coffers/nykhthos/phyrexiantower but im guessing youre okay with that hahah. (did not see any nonbasic synergy, cut command tower for a swamp? since you have swamp/basic synergy?)

Virtus the veiled doesnt seem like a good inclusion, you have to hit with him after all and youre not running unblockable anyway because thats not the theme. Also, Archfiend of Despair does exactly what you want in this deck. Was looking through what to cut for it, maybe some graveyard interaction can go? I dont know how much grave stuff your playgroup does but seems like something you dont have to worry alot about generally. What does Karn do in this deck?

Yes i do for sure, i usually do 35 lands + arcanesignet + sol ring. And if i play a mono or dual color deck i throw in a Throne of Eldraine (the artifact). I dont know what kind of group you play with the decks seems pretty strong. I see youre running alot of things that sac creatures, but you're only running 14 creatures! Without token generation/lots of sacrifice fodder i think you can cut alot of that sacrifice stuff.

Never run less than 35 lands, lowest ive gone is 33 if my commander is cheap and/or makes mana