Murders at Karlov Manor has some returning mechanics, so here are some rule refreshers: Face-down cards are in the set, so a reminder: normally, you dont have to reveal what any face down card is, but if your Commander is turned face-down, it is still a Commander card that deals Commander damage
Teferi's Ageless Insight
The discard effects are what you want to zero in on here, with a notable one being the combination of Nath with Sadistic Hypnotist to Mind Twist your opponents
Board control specialist that punishes wide boards
Though power creep has surely made this six-mana creature somewhat obsolete, it is still notable for being a dual Magic lord, boosting both Treefolk and Saproling creatures, and it also serves as an effective mana sink via its kicker ability, which can be used to invest when you cast it, which will creature that many Saproling creature tokens