6 mana is just a lot though ... 5 mana happens quite often, but 6 is not easy to hit. The deck runs 21 lands + 4 Flower//Flourish, plus three Legion's Landing that can flip to lands, but it's empirically not easy to get to six mana. In fact I've played my fair share of games stuck on 3-4 or even 2 mana. Convoke (especially with Emmara) goes a long way to making it so that the deck can operate semi-OK with 2 lands, but Carnage Tyrant doesn't have convoke. I went down to 1 Knight of Autumn and up to three Vivien Reids, that might be the best option.

Really nobody played with Treasure Map? I'm especially interested in, what is the purpose of this card in a sideboard anyway? Is it a generic grind card? How many copies of it is ideal?

I just had Unmoored Ego played against me for the first time. Grixis control opponent named Carnage Tyrant. I presume it's because there's no other way he can beat the card (he could trade Doom Whisperer for it I guess, but that's it). Opponent died to 1/1 token beatdown though, having not drawn his sweepers or boarded them out.

I'm honestly not a fan of Unmoored Ego, since it's card disadvantage. Cards like Slaughter Games don't have this issue, but still nobody plays it in Modern.