There are a few cards that stand out as being a bit odd to me.

I think that Bontu's Last Reckoning is a rough card to play in a multiplayer game. Even with 8 mana rocks, not being to untap lands the turn after casting it is rough because you run the risk of quickly falling behind your opponents. Marchesa does take away some of the risk by bringing back your creatures while your opponents' will theoretically have none of theirs left. Still, I don't like the idea of denying myself even just 3 mana like that.

I like Reins of Power , but when I experimented with it in a Marchesa deck that I built a while back I found that it was often awkward to work with. If I had any free sac outlet creatures I would have to get rid of them before using it, and if the chosen opponent found a way of killing the creatures with counters while controlling Marchesa they would come back under his control. In the end I cut the card because I just found it to not be what I wanted tot draw most of the time. There are some blow-out plays that it can help you pull off but in the end I replaced it with Fire Covenant .

Karn, the Great Creator doesn't really do much for the deck. I do see that you have a sideboard but there are a lot of groups that don't allow the use of sideboards, so that part of the card is pretty meta dependent. I'm also assuming that you are running it as a stax effect for some of the other decks you play against. As long as your group allows sideboards I guess it works as a tutor, but if that's the case you may want to include one or two more silver-bullet artifacts that you would be able to tutor for. Duplicant , as a creature that can exile indestructible creatures, would probably be one of my first picks. Nevinyrral's Disk as a way of dealing with enchantments would also be a high pick for me.

Rekindling Phoenix strikes me as having minimal uses in terms of utility, although it does interact a with Flayer of the Hatebound 's effect. Aside from that, it is mostly just a body for combat that can potentially come back on its own after a wrath effect. I would probably look to cut it for a more relevant cards as you develop the deck, but if you ended up adding cards like Warstorm Surge and Skullclamp that would make the Phoenix a little more keepable as a potential value engine that doesn't rely on Marchesa being out.

If you can find one, Aura Thief is also a handy way for grixis colors to deal with enchantments. Steal Enchantment is also an option.

SaberTech

I'll agree with Bontu's Last Reckoning on that part, I always use majority of my mana each turn. However, it is a 3cmc boardwipe. Which is huge.

Reins of Power is in my deck because of popularity of Cyclonic Rift and In Garruk's Wake in our meta. Always unexpected, always lots of fun to use.

Karn, the Great Creator is an oddball to me here, too, however, I didnt draw him in my last plays, so can't say how efficient his presence is (unlike Narset, Parter of Veils on turn 4, bringing collective frown from everyone who played their Sylvan Library ). Might switch him to Ashiok, Dream Render . And no, oir playgroup doesnt mind sideboard tutoring, as long as it is not duplicate or bs-lock (Lavinia and knowledge pool, shimmer and urborg, lettuce for karn).

I was going to put Duplicant , however, I feel like I have plenty of exile effects already. Will keep him ready for playtest, though.

I like Rekindling Phoenix for his pseudo-undying, making me chump-blockers and sac fodder, since if he comes back with counter, his token cannot trigger without phoenix in graveyard. Surprisingly, with amount of idestructibles my opponents are running, only exile effect they tend to run is Merciless Eviction .

I had Warstorm Surge for some time, but pulled it out. It is only a side effect, and is very inconsistent here. I rely on creatures revival from combat, not on aristocrat tactics. One of the opponents is running Ikra Shidiqi, the Usurper and Tymna the Weaver lifelink deck, and dealing 15-20 to the face against him is more important than random damage from surge.

Will definetely consider Steal Enchantment , however, so far the only enchantment I had problem with was Omniscience , though,it is always acting as a singleuse, dumping all big threats all together, finishing the game.

I've been trying to remember how I built my old Marchesa deck because I never got around to writing the list down before taking the list apart.

I remember having a small Wizards package. Sage of Fables was important because it made Marchesa enter the battlefield with a counter already on it. Puppeteer Clique and Glen Elendra Archmage became infinite sac fodder with the Sage out. Viscera Seer was one of my sac outlets. Snapcaster Mage for reusing spells. And Vedalken AEthermage could tutor up any of those cards.

I also used a lot of artifacts. Arcbound creatures always had counters on them so they always came back on top of putting counters on my other artifact creatures like Duplicant and Noxious Gearhulk .

Carrion Feeder was one of my favorite sac outlets because being able to put counters on itself made it hard for opponents to get rid of.

I won by either setting up an infinite sac combo that killed with Goblin Bombardment , grinding opponents down with Flayer of the Hatebound , or creating a massive board by stealing opponent's dead creatures with Sepulchral Primordial .

SaberTech

Interesting take. I actually removed Sage of Fables from the list, because I have only 3 wizards in entire deck, abd it is not too consistent. Noxious Gearhulk has dreaded lifegain (I struggled quiet a bit with lifelink on 6/6 army from Dreadhorde Invasion , and had to sac it on 5/5) and 7cmc is not something I am excited about. I considered creature-based removal in face of Ravenous Chupacabra , but ultimately decided against it. Will probably put in Duplicant though, because his mimic ability is amazing again stompy. Honestly, not thrilled about Carrion Feeder . He needs a lot of sacrificial fodder, unlike Yahenni, Undying Partisan .

I also remembered why I actulaay put Karn, the Great Creator in deck. With his +2 loyalty lands become 0/0, and any creature with activated ability is switched off.

Karn's abilities only work on artifacts. Are you running Liquimetal Coating or Mycosynth Lattice in your paper list?

You honestly don't need any other wizard other than Marchesa for the Sage to be worth including. It's worth it just on its own as protection for Marchesa and it comes with the bonus of turning extra +1+1 counters on a creature into cards.

My build was heavily focused on sacrificing my own cards for value. I like building grindy, synergistic decks so I was using Carrion Feeder for it's ability to sac my stuff and didn't really care about how big it got to use as an attacker. The counters it gave itself just made it harder to remove when Marchesa was on the board.

I know I ran a lot of ways to use my life total as a resource, so Noxious Gearhulk 's lifegain was actually useful for when I wanted to bulk up some life to sink into something like Necropotence or Toxic Deluge . Pretty sure I also ran Miren, the Moaning Well as another way to gain some life as well.

SaberTech

Hmm, yes, you are right. I misread that. Karn is probably going away than, leaves space open for Duplicant .