This deck is based on The Commander's Quarters competitive Teysa deck: https://www.youtube.com/watch?v=rZhsnejL30g, with my own modifications.
Note: i want to add smothering tithe and enlightened tutor to this deck and I am waiting to see if they will be in the white commander spell book before I buy them.
Modifications
0) +1/+1 counter generator:
A) Cathars' Crusade: this card synergizes with all my token generators because whenever on of my creature enters the battlefield, put a +1/+1 counter one each of my creatures, so for each creature token i get an extra +1/+1 counters on all my creatures.
1) Recursion:
A) Athreos, God of Passage: he lets me recur creatures back to my hand after they die and when Teysa is in play, my opponent has to pay 3 life twice for the creature stay in the graveyard. The coolest thing is that my death triggers still happen, even if it goes to my hand.
B) Luminous Broodmoth: she brings all my nonflying creatures back from the graveyard and gives them a all flying, plus their death triggers still happen.
2) Token Generation:
A) Elenda, the Dusk Rose: when she dies, i get X 1/1 creature tokens where X is her power and she gets a +1/+1 token every time another creature (including my opponents) die. It synergizes with Cathars' Crusade's +1/+1 counter generating abilities and Teysa's double death trigger ability.
B) Hangarback Walker: when it dies, i get X 1/1 creature tokens where X is the amount of +1/+1 counters on it and i can pay {1} and tap it to give it a +1/+1 counter.
C) Wurmcoil Engine: with Teysa out, when my Wurmcoil Engine dies, i get 2 3/3 life link creatures and 2 3/3 death touch creatures. It synergizes with Cathars' Crusade's +1/+1 counter generating ability and Teysa's double death trigger ability, which results in 4 7/7 creature tokens.
D) Seraph of the Scales: she has an afterlife 2 effect, which can give me 4 1/1 tokens with Teysa is out on the field.
E) Basri's Lieutenant: he synergizes with Cathars' Crusade, as whenever a creature with a +1/+1 counter dies, create a 2/2 knight with vigilance, so with Cathars' Crusade all my creatures will have +1/+1 counters on them, so each death creates two 2/2 creatures, with Teysa on the board, plus it creates 2 Cathars' Crusade triggers.
3) Damage:
A) Vito, Thorn of the Dusk Rose: he allows me to deal damage to a target opponent when i gain life. So my when my tokens gain life from their lifelike, I can deal damage to a target opponent.
B) Massacre Wurm: When Massacre Wurm enters the battlefield, he gives -2/-2 to all my opponents' creatures and he deals two damage to a target opponent when one of his creatures dies or 4 damage when Teysa is out in play.
The -2/-2 gets through indestructible because creatures that are indestructible, still die when their toughness goes to zero. Plus this combos with Toxic Deluge, as toxic deluge can get through indestrucable and hex proof creatures.
C) Kokusho, the Evening Star: when he dies, he deals 5 life to each opponent and I gain life equal to the life lost this way. So if i have Teysa on the field, i deal 10 damage to each player and I gain 30 life. Vito, Thorn of the Dusk Rose on the field, i get a damage trigger that equals my life gained.
4) Wraths:
A) Merciless Eviction: My friend plays slivers and once he has Sliver Hivelord on the field it's game in a 1v1 match. So, I put Merciless Eviction in this deck to deal with mass indestructible effects. I hate how it prevents my death triggers, but sometimes, desperate times call for desperate measures,
B) Toxic Deluge: I put Toxic Deluge into this deck as another way to deal with indestructible creatures, while also allowing my death abilities to trigger. Plus, the life loss caused from toxic deluge is mitigated from the life gained from my tokens.
5) Mana Ramp:
A) Land Tax: I took out the 1 & 2 low mana token generating creatures to make room for the above modifications and, as a result, I have a higher my mana curve than the original deck. Land tax helps mitigate this mana curve increase by allowing me to play a basic land card each turn, which will allow me to play my creatures on curve.
6) Tutor:
A) Grim Tutor: it came out in M21 and it is $12 USD and demonic tutor is $40 USD, so i went with the cheaper option.
7) Draw:
A) Mangara, the Diploma: he is just a fun way of drawing cards as whenever 2 or more creatures, i draw a card and whenever an opponent casts their 2nd spell, i draw a card.
B) Sensei's Divining Top: the top was one of my first MTG cards, as I started playing during Kamigawa, so i am super stoked in having the opportunity to play it in commander.