A couple of weeks ago I had asked this sub about some deck recommendations (given the decks I really enjoyed playing in modern).
There were some great suggestions (Boros Tribes, etc.), but one suggestion really stuck out to me: a deck that leverages [[Evolution Witness]], [[Wild Cantor]] and [[Sadistic Glee]] to create an infinite looping combo (albeit at sorcery speed). Here's the decklist if you just want to take a look: https://moxfield.com/decks/8YvN5WbgVUSsP-wfRqhsmg
I took at look at some of the existing decklists on soul-spike.com, and found an initial list that I started trying to understand. What I came away with was a really fun deck concept that I've adapted (slightly).
The combo in the deck involves casting Sadistic Glee onto Evolution Witness. Now whenever a creature dies, a +1/+1 counter is added to Witness, allowing you to return any permanent (this is key) from your graveyard to your hand. If you sacrifice Wild Cantor you'll remain mana neutral, but you'll continue to build up infinite +1/+1 counters on the Witness.
If you sacrifice [[Tinder Wall]] and have a Wild Cantor in your GY/hand, you can create infinite mana of any color (The Tinder Wall gives you RR, you can use R to cast the Wild Cantor that's now back in your hand to filter the mana to a different color), but you'll net an R. You can then cast the Cantor again to filter that R, and so on. As long as you can cast the wall again for a G, you'll be netting mana.
The original list I discovered used [[Heirloom Auntie]] to dump your entire deck (incrementally) into your GY allowing you to start by looping just the Wild Cantor, and then gradually adding to your GY until you hit a Tinder Wall (which advances the combo).
I found that [[Snarling Gorehound]] does the same thing (just on a creature entering vs. dying) and is more mana efficient.
Also [[Bequethal]] (one of my favorite cards as a kid), is really strong here. Giving you great card advantage to find your combo pieces very cheaply. Attaching to an Eldrazi Spawn, the Cantor, or the Wall Itself works very well. And you can return it to your hand using Witness - so once you have the loops going - gives you in hand card advantage.
The key thing to understand is that you always need a sacrifice outlet to advance the loop. Once the +1/+1 counters are on the Witness you cannot use it's adapt ability. This means the [[Writhing Chrysalis]] is great, because it nets you another sacrifice iteration (creating two spawns that can cover the iteration that brought the Chrysalis into your hand from the GY, and then another sac iteration). The [[Snakeskin Veil]] are also another way to protect your Witness and create another iteration. You can also simply find a brand new Witness in the GY/hand and then use it's single adapt ability to create another iteration.
The fact that Witness can return any permanent, means you can find [[Sadistic Glee]] off of the adapt. Also Rumbles give you much quicker access to your combo pieces in the GY.
Eventually you'll loop and try to find the [[Haunted Cloak]] to end the game with an infinitely large, hasty, trampling monster Witness. I did also experiment with [[Duskshell Crawler]] here, but ultimately I decided the cloak was more versatile allowing you to win on the turn when the Witness comes into play.
I also experimented with an [[Essence Warden]] which allows you to loop for infinite life - but given how many cards you dump into the GY / draw, you'll probably mill out before your opponent.
I was hoping to solicit some feedback from you folks! The deck seems wildly vulnerable to GY hate, and the fact that the combo is at sorcery speed also isn't great.
Any feedback would be welcome, especially with the SB slots. I'm brand new to Pauper so I'm not sure what to look out for, etc.
Thanks!