Late last year I built a Mimeoplasm Ooze Tribal EDH deck for fun and while I haven't played it much this year it has always been at the back of my mind especially when fun new oozes like Umori, the Collector, Oran-Rief Ooze and the upcoming Biowaste Blob and Slurrk, All-Ingesting (Commander Legends) are added to the game alongside the slime-tastic Prime Slime Secret Lair (i'm not usually a big fan of the Secret Lairs but in this case I made an exception) being released. Luckily in a bit over a month's time there will be the perfect opportunity for me to whip the deck back out again - my LGS's end of year Tribal Event (this year also featuring a Brawl/EDH tribal variant), it's similar to the Halloween event I attended a short while ago but bigger and crazier (always a highlight of my MTG playing year, big props to the Card House crew) and I can't wait to ooze into action for it.
In order to make things easier for players the deck building rules are a little different from normal -
1. The deck size is 60 cards (like in Brawl or Oathbreaker)
2. The banned list is normal EDH + Tribal Wars (see below*)
3. The deck must contain 20+ cards of the chosen Tribe (changelings are ok substitutes at a pinch, useful for the less populous tribes).
4. Creatures outside of the chosen Tribe aren't allowed unless they reference the Tribe (IE. Dragonspeaker Shaman is a Human Barbarian Shaman who references Dragons so it would be okay in a Dragon Tribal deck).
* The Tribal Wars banned list is as follows:
Arboria, Circle of Solace, Endemic Plague, Engineered Plague, Moat, Peer Pressure,
The Abyss, Tsabo's Decree, Umezawa's Jitte and Unnatural Selection.
A general rule of thumb is - don't run any cards that can choose to hate on a tribe.
Also the format is very loose in nature and outside the box concepts are not only accepted, but encouraged, in previous years we've had "Tribal" decks built around man-lands, Phyrexians and even pop culture references like Game of Thrones and Shrek. A good (or whacky) idea and a chat with our friendly LGS owner (shoutout to Kev) is all it takes to find some wriggle room in the rules for a good cause.
How to deck build:
Choose a Tribe - go for your favorite, extra props to people who pick a more unusual option (Goblins, Elves, Merfolk, Zombies, Humans, Slivers etc. are all great but they are all done to death).
Choose a Commander - (this can be interchangeable with the 1st point) the Commander should be a part of your chosen Tribe or at least reference the Tribe (IE. Thelon of Havenwood for a Fungus tribe), luckily for the more out there options there's always Morophon, the Boundless as an omni tribal Commander option.
Track down as many on Tribe members (or Tribe referencing) cards as possible - Going through your binders/boxes etc. is always a good 1st port of call but for a more in depth dig (useful especially for older cards, many of which had their Tribes changed by oracle rulings) i'd recommend a site like Scryfall (has a many more options that WotC's own Gatherer) and doing a search for the Tribe's type and for mentions of the Tribe in card text.
Cull your list down - You have 1 commander, minimum 20 Tribal creatures and probably 22-24 lands, so you need to work out what to do with the remaining ~15-17 slots - more Tribal creatures? Tribe referencing cards? Ramp? Normal utility cards (removal/card draw etc.)?
Have fun with it - card/sleeve alters, costumes, any and all craziness only adds to the awesomeness of the deck.
In my case I was lucky enough to have already built a Tribal EDH deck for normal 100 card EDH play so for the event I just have to slim things down. Some easy-ish cuts - 10+ lands, all creatures which don't relate to the Tribe (it's a bit sad to lose the Necrotic Ooze graveyard package but whatevs), a few Tribal boosting cards that are too unreliable in a format where everyone is playing Tribal (sayonara Coat of Arms, Faces of the Past ...), a few of the "worst" Oozes (goodbye Mephitic Ooze, Mwonvuli Ooze ...) and after 40 cards are gone i'm done and this is the resulting list -
The new Commander Legends Ooze pair.
I hope you enjoyed and were informed by this article. How about you? Do you have a Tribal EDH deck (60 or 100 card)? If so what is it and how does it work? If not what type of deck would you like to build in the future (maybe after Commander Legends opens up some new options)?