commander · Kathril, Aspect Warper
Symbiotic Swarm (C20).
An Abzan graveyard keywords deck led by Kathril, Aspect Warper, fill your graveyard with creatures carrying powerful keywords, then cast Kathril to distribute those keywords across your entire board and attack with an unstoppable army.
The Commanders
Symbiotic Swarm is an Abzan Commander deck built around graveyard-loaded keywords and Kathril's ability to distribute them. The game plan: fill your graveyard with creatures that have every relevant keyword, cast Kathril, and watch her enter as a 14/14 with flying, first strike, double strike, deathtouch, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance. Then the rest of your army gets counter-based copies of those keywords too.
Kathril, Aspect Warper costs {3}{W}{B}{G} and is a 3/3 Nightmare Insect. When she enters, for each keyword ability among creature cards in your graveyard, put a counter corresponding to that keyword on any creature you control. Then put a +1/+1 counter on Kathril for each counter placed. With ten keywords in the graveyard, Kathril becomes a 13/13 (base 3/3 plus ten +1/+1 counters) and distributes the rest of the keywords to your other creatures. One swing from Kathril with double strike, indestructible, and hexproof is frequently enough to one-shot opponents.
Key Cards
Buried Alive
The deck's best graveyard filler. Buried Alive costs {2}{B} and puts three creature cards from your library directly into your graveyard. Three creatures in the graveyard before Kathril enters means three keyword contributions without drawing them. The optimal Buried Alive package: Zetalpa, Primal Dawn (flying, double strike, vigilance, trample, indestructible), Odric, Lunarch Marshal (a Human to dump), and any lifelink or deathtouch creature. One Buried Alive followed by Kathril makes her an 8+ power double striker with indestructible on the first cast.
Zetalpa, Primal Dawn
The keyword motherlode. Zetalpa is an 8 CMV 4/8 with flying, double strike, vigilance, trample, and indestructible, five keywords on one card. Mill or tutor Zetalpa into the graveyard before Kathril enters and you've got five of the ten keyword counters Kathril wants for maximum power. With Zetalpa in the yard, Kathril enters as at minimum a 8/8 with five keywords before any other creatures are counted. Buried Alive plus Kathril on the same turn reliably comes together by turn six.
Nethroi, Apex of Death
Mass reanimation that gives the deck real staying power. Nethroi mutates over a creature for {4}{W/B}{G} and returns up to 10 total power in creature cards from the graveyard. After a board wipe, Nethroi rebuilds your graveyard of keyword creatures on the spot. The deck can eat several board wipes because Nethroi restores everything in one activation, including the graveyard setup that makes Kathril scary. Nethroi is also the alternate commander for players who like reanimator strategies.
Dauntless Avenger
Targeted reanimation for keyword creatures. Dauntless Avenger costs {2}{W} and returns a creature card from your graveyard whenever a creature you control dies. With a graveyard full of keyword-bearing creatures, every death turns into free reanimation. It gets nasty with Kathril: kill your own Kathril with a sacrifice outlet, Dauntless Avenger brings back a keyword creature, and you recast Kathril with even more counter sources.
Tayam, Luminous Enigma
Counter-based recursion engine. Tayam costs {1}{W}{B}{G} and lets you remove three counters from permanents you control to mill three cards and return a card with mana value 3 or less from your graveyard. With a board full of creatures wearing +1/+1 counters from Kathril, Tayam turns spare counters into graveyard recursion. Pull two counters off a big Kathril and one off any permanent to mill three and get back a key two or three drop. Tayam keeps the deck stocked with options even under pressure.
How to Play
Look for Buried Alive or Satyr Wayfinder in your opening hand to start stocking the graveyard. The turn you cast Kathril is usually your biggest one, so you want six or seven keywords sitting in the graveyard first. Protect her hard the turn she lands: she's the win condition and needs haste or protection equipment to threaten lethal. After one swing, most opponents at 40 are down to 20 or less from Kathril's boosted power with double strike. Nethroi handles the rebuild after board wipes. The deck wins on sheer keyword redundancy, and opponents need exile, not just destroy effects, to get rid of Kathril for good.
