This is a semi-competitive combo deck that can threaten to win games very quickly if no one interacts with it (when gold fishing the deck can consistently win turn 7-9 on an average hand or turn 4-6 on its fastest draws, although you could probably push for turn 3-4 kills by adding more busted fast mana). It also has a lot of different ways to combo that are easy to interact with to avoid feeling stale or, "un-fun," as some might put it. It will often try to win multiple times over the course of a game. The deck will rarely fold to one of its combos being disrupted and can hold its own with its fair gameplan generating etb value off of Aleshas ability while looking for a new option. Still, probably check with you playgroup to make sure they are okay playing against a fast infinite combo deck before bringing it to a table.
Mulligan Advice
Casting Alesha on turn 3 is the most important early play. Avoid keeping hands with 2 lands as much as possible but hands without acceleration are fine. If your 6 has the mana to cast Alesha you should probably keep it. At 5 maybe consider keeping hands without the mana for Alesha.
Hands with Buried Alive and mana to cast alesha are a snap keep. These hands will produce the decks fastest kills. Usually you wait till turn 5 to cast Buried Alive so you can cast it and reanimate a card from the pile in the same turn. When setting up a buried alive combo remember Redcap can play the role of both sac outlet and blood artist, your most common pile will be Karmic Guide + Revilark + Murderous Redcap
Hands with Mentor of the meek are also a very good as it will often draw you the rest of the pieces you need.
Hands with all interaction or all protection for nonlands are usually worth a mulligan on a 7, especially your first 7
When choosing cards to bottom prioritize keeping proactive cards to fill roles in your combo over protection/interaction
Combos
With Alesha + Master of Cruelties you can knockout any player who doesnt have blockers up
Karmic Guide + Reveillark + Sac outlet can kill in a variety of ways. Any blood artist effect, Murderous Redcap, or Gonti are all lethal with those two
Speaking of Redcap it can combo in a number of ways too. Redcap + Anafenza + Sac outlet is the easiest. Redcap + Nim Deathmantle + Ashnod's altar works too. Remember if you have a blood artist but no sac outlet that redcap's etb can target itself.
Kiki-Jiki has lots of ways to kill people. The classic is Kiki-Jiki + Felidar guardian / Restoration Angel / Zealous Conscripts for infinite hastey copies. Fable of the Mirror breaker is a more "fair" (i.e can't go infinite) version of the card but still very powerful.
Sun Titan + Fiendhunter + Sac Outlet can give infinite etb/death triggers, as can Leonin Relic-Warder and Animate Dead, killing with a blood artist effect
Nim Deathmantle and Ashnod's Altar can combo with Murderous Redcap as stated above bot there are other ways this combo can work as well with a bit of help from token generators and a blood artist, outside of Redcap this combo harder to pull of though as it needs more pieces.
Leonin Relic-Warder and Karmic Guide/Revilark can also loop a mana rock for infinite mana, not frequently useful but this can draw you your deck with Mentor of the Meek. A very fringe combo, but worth noting.
Preston feels very silly when its in play but usually they don't enable combos on their own, just makes it much easy for the combos to go off. For example Animate Dead + Leonin Relic-Warder doesn't kill all by itself but with Preston in play it can generate and arbitrarily large number number of 0/1's which still doesn't kill, but is does make converting that loop into a kill a lot easier.
Maybeboard
The cards in the maybe-board are options you can slot in if you want to change how the deck plays. You could replace some of the tutors for more combo pieces or less consistent tutors like gamble. You could trim the combo cards to lean more into a midrange game plan with more interactive cards and sources of card advantage. You could even cut on the interaction in the deck and in more combo cards or tutors to go all in on combo.
In terms of cards in the main deck to cut for your desired slot-ins, I think you have a couple directions to go. Option one is to trim the fat from the combo cards. In particular Nim Deathmantle and Sun Titan are both pretty specific in the cards they combo off with and don't interact with your game plan as well. Sun Titan can be nice as a fair target for Animate Dead, but at 6 mana casting it feels pretty bad unless its to win the game with its combo. Option two is to cut the Sunforger package . This might honestly be a strict upgrade to the deck but Sunforger is a pet card of mine so I like to play it. Killing someone with commander damage isnt something this deck does often but Alesha carrying Sunforger hits like an elder dragon. If you aren't playing Sunforger I think Eerie Interlude, Anguished Unmaking, ed Elemental Blast, and maybe even Teferi's Protection start to be on the chopping block. Although Teferi's Protection does have being the only card that saves your graveyard from a Bojuka Bog going in its favor. If you have a lot of cards you want to slot in taking both options may have be a good idea.
Powering up the deck
I would probably describe this deck as a 7 on the power scale, with games where you draw Buried Alive feeling more like an 8. If you want to push the deck into that 8-9 the biggest change would be adding more fast mana. Ancient Tomb, Mana Vault / Crypt, the legal moxen, that kind of stuff. You should also add in more powerful tutors like Ad Naus, vampiric tutor and imperial seal, wishclaw talisman, ect. These changes can be accomplishes using the same cuts as above, although the fast mana can replace some of the land slots, you might even consider going as low as 35 lands in this build since it will be trying to combo so fast. If you are going into a CEDH meta you can tailor the decks interaction to that kind of meta as well, probably adding Pyroblast at a minimum and more stax pieces.
Custom Categories
The deck uses the following custom categories (listed roughly in order of size) to group cards by their role in the deck. Note that cards can be in multiple categories
Lands: self explanatory
Combo Pieces: These cards can be part of a combo
Interaction: Cards you can use to interact with your opponents boards
Protection: Cards you can use to protect your board or shut off interaction on your combo turn
Sunforger: Cards you can cast off sunforger
Sac Outlets: Cards that can sacrifice another creature for free - an important interchangeable piece of many combos
Card Draw: Cards that dig you deeper into your deck, note that these are mostly looting effects and don't strictly generate card advantage but often feel like they do
since you can usually get value out of whatever you discard
Tutor: Cards that let you search your missing combo pieces
Graveyard Value: Cards that can get you value from or in your graveyard
Discard Outlet: Cards that let you put cards from your hand in the graveyard
Blood Artists: Cards that deal damage to opponents when creatures die - an important interchangeable piece of many combos
Ramp: Cards that accelerate your mana, this role might need more cards but the 2-mana acceleration point is less important for this deck to hit since Alesha is a 3 mana commander. More ritual affects to play her on turn 2 might be worthwhile though.
Evasion Sources: Cards that give Alesha evasion. Being a 3 power first striker is usually enough to safely attack someone with her but sometimes you need more.
Value: Cards I couldn't fit anywhere else because they are just generically strong (FotMB) or I'm still working out their role (Preston)
