Alternate Reality Invasion: Allies fight off Phryexian hordes.

I honestly didn't follow MTG story long enough to learn what happened to Phyrexia, Dominaria and Mirrodin. But I loved the idea of the plane being a hellscape of artifacts and infected flesh serving an industrial war machine. So my take is the Legacy Weapon was used to ravage Phyrexia and New Phyrexia (corrupted Mirrodin) is the new seat of Phyrexian power.

A second invasion is now in the works and another staging plane (like Rath) is being used to attack Dominaria. It's up to some planeswalkers and an allied coalition of Kor, Humans, Merfolk, Birds, Goblins and Elves to repel the invasion. Vampires are consumed with their own personal politics but may be swayed to the alliance. Of course alliances can always be broken...

The Yavimaya is still doing her forest-y protection thing like in the first invasion. No Kavu this time :( The Riptide Project was rebooted. Rebels were in the midst of violent action against such dangerous repeating of history. They may feel some vindication that Phyrexian agent sabotage once again have loosed a slivers plague to the malaise of all.

The draft-able archetypes are mostly broken into guilds and many are creature tribal. See the playtest tab for some examples of decks. The features of the colour identities I am using to guide the cube composition are summarized as follows:

: PHYREXIA! (-1/-1, Artifact, Zombie)
: Goblin
: Rebel
: Illusions (Creature-type changing)
: Elf
: Vampires (Madness)
: Cycling (There are a bunch of Allies here too)
: Bird
: Merfolk (+1/+1 counters)
: Infect (Don't forget about Virulent Sliver)
: Sliver (escaped to also)
: Cat
: Mill (Zombie, Rogue)
: Land (Destruction, Graveyard)
: Cleric