I'm overly excited for what Patch 7 will allow modders to create, and have been wanting a plasmoid race for awhile. there are already mods that let you become oozes and slimes like the vessel class, but you're still human until you transform. I think most of the 5th edition passives and traits are easy to make, like reduce or enlarge for size, shape shifting or disguise self, and the resistances to acid and poison and such. I think the hardest part would be modeling the tav to look either like an ooze, or a slime-skinned humanoid model.
After looking around a bit, there's already a mod called Playable Genasi Race that has a slime genasi, which might make creating the plasmoid easier? I love genasi but would love a standalone plasmoid!
Here's the 5th edition break down for anyone who's curious or wants to make it: https://dnd5e.wikidot.com/lineage:plasmoid
Thanks!