Our ultimate game plan is to reduce our opponents' life totals to 0 by choking their ability to play so tightly that they can no longer play the game and inevitably die to simply existing. We accomplish this by playing life taxing effects for various aspects of playing magic. "If an action can be made in magic, then our opponents can pay in blood" is the philosophy of this deck. We can punish people for drawing cards, existing (i.e. Upkeep effects), casting spells, activating abilities, having artifacts, having creatures, tapping their lands, not tapping their lands, or for simply playing lands. We can punish any decision, any action a player makes with a myriad of cards.
What this deck does well
This Mogis deck does a great job of locking people out of games by shear brutality. We have stacks pieces like Trinisphere, Sphere of Resistance, and Nether Void alongside of the amazing hate pieces in Null Rod, Cursed Totem, and Torpor Orb to make the game come to a grinding halt. We also have cards like Spellshock and Pyrostatic Pillar to punish greedy play from our opponents, bringing them ever closer to the guillotine's rope being released. Ad Naus decks tend to have many issues dealing with their life totals being pressured so aggressively. Furthermore, we stop most combos dead in their tracks due to them having too many moving parts or relying on many abilities or actions that we punish. We do have some interaction at instant speed, but that is not really our plan.
Do we have combos?
We do! We have 4 in the deck:
1) Bloodchief Ascension + Mindcrank
After Bloodchief is online, any life loss or card put into graveyard will kill your opponent. With Mogis on the board, he sets up the quest counters quickly (1 turn cycle if no one sacrifices anything to him) and when Bloodchief is online, your opponent's choice of sacrificing or not does not matter as they die one way or the other. (Sacrificed creature goes to GY and triggers Bloodchief, loops with Mindcrank, OR they take 2 from Mogis, triggering Mindcrank, triggering Bloodchief and looping)
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2) Vito, Thorn of the Dusk Rose + Exquisite Blood
This combo is just Sanguine Bond + Exquisite Blood combo but 2 mana cheaper. If an opponent loses life (which they will in our deck), then everyone dies.
3) Karn, the Great Creator/Null Rod + Mycosynth Lattice
If you can keep the board clean of creatures (which you usually can), you lock your opponents out of being able to activate anything (even lands). Null rod also locks yourself out, but with Mogis and other triggers on the battlefield, it is an inevitable end to the game. Don't forget that your opponents can't Force of Vigor you for free with Mycosynth Lattice as Lattice makes all cards, even cards in hand, colorless.
4) Goblin Sharpshooter + Splinter Twin
So this one is a little more complicated and requires a target to die to start the loop. First you make a copy of sharpshooter, then the copy needs to kill any target (or have a bolt or something to kill another target that isn't the original sharpshooter). This will untap both sharpshooters and now you have infinite damage online. Make another sharpshooter. One of the copies shoots an opponent and the other shoots itself untapping the other 2 sharpshooters. Repeat the process.
Mulligans
This deck can be difficult to pilot for many reasons, but mulliganing has to be the hardest part. Deciding whether or not to mulligan takes a lot of knowledge about the decks around you. One hand that is perfectly keepable against one group can be a hand that has to be thrown away in others due to the nature of playing to the board and not having any form of interaction (our hate spells) for what is present at the table. We will discuss some of the match-ups later and what cards are match-up appropriate. That all being said, sometimes you have enough generic hate cards that are proactive and start the clock early to keep the hand anyways.
Other Difficulties of playing Mogis
You must accept that it is very easy to become the villain at the table, and therefore eat a lot of the ire of the rest of your pod. It happens frequently. You cannot get annoyed by that fact. Politics are still a part of cEDH. You may need to point out to your angry opponents that someone else is the actual threat at the table, even though they can't see it and they can clearly see what you are putting down. Keep calm, I get it, you are probably a red mage if you are here. I am too.
Another issue that arises is that you don't have a lot of stack interaction. There are times where you literally can't interact with your opponent that's trying to combo. It happens. Get over it. Play another game - they go by pretty quickly!