I love the ideas for all these champions! The only issues i have are the names and titles. They just seem bland and generic to me.
For Pla'Sma, i'd suggest looking at Rek'Sai. her race is called the Xer'Sai, and it can probably be inferred that other races share the same end part (the Sai part), but have a unique name for the first part. Of course, for the race, it is not going to be Xer as the first part, as there is a race known as the Zz'Rot. However, these are primeval and small beings, so maybe for larger races, Xer is the right title (social justice much?) By looking at the names of current void characters, they do not represent a word such as Pla'Sma does. One thing I've noticed is that, with the exception of Cho'Gath, void creatures have 3 letters for each half of their name, so focus on one part at a time. All voidborn have a hunger, or purpose, and for Pla'Sma, it is not as clear. Back to names, however. I like the beginning sound of Pla'Sma, but I think the end part can change. The beginning part, try out Plo and Plu, maybe? Also, his kit is off the convention, as all voidborn deal true damage in their kit, except Kha'Zix, and all void-related champions stack something.
The next 3 have kinda generic names that you didn't put thought into. Think of what Riot would name it, first. Think of their current naming conventions. The titles for these are also pretty bland; we have too many gods in league, and I personally think we should change them up. The undead are cool, since they can still be expelled, but people like Bard, Kindred, and the like are kinda bland to me, since it is not clear as to why they came to the league, and lack background. Gods in league can be cool, but let's be honest, any more and we become smite. If you ABSOLUTELY need gods in your ideas, I'd put a bit more thought into the names; make them fit the title and lore, but not make them literal words. Kat seems like a good first part, but Enigma doesn't work well.
The last one, Unfallen, seems like a good concept, BUT his name seems more like a title. When Jhin was not yet released, people thought he would be Deadeye, The Jhin, or Jhin, The Deadeye. You see how the second one seems more like a champion than Deadeye, The Jhin? It isn't as clunky. The final title was better, though, as The Virtuoso. However, this isn't the case with Unfallen, as The Risen Prince isn't a name either. Try to stick to the one word convention if you can, and if you can't stick to it, use 2 words at the max, like how Ao Shin/Aurelion Sol are. The first/second word is shorter, and doesn't have much grandeur or importance.
Overall, your ideas for a kit are really well thought out, you just have to rethink the names and tweak numbers to make them REALLY shine. Thanks for reading, and sorry about the criticism!
[slayer-pantheon-thumbs]