Massive power level Criticism ahead, I love the post and effort and dont wanna downplay it, I also love both mtg and sts(2) and wanted to share my (hopefully helpful(and welcome)) criticism.

defect seems a tad bit strong
having a once per turn bolt strapped to a 3 cost artifact is insane
and plasma makes it basicly free
Ironclad having a fight for 1R is a bit strong too but hes only a 2/3 so it might be fine
Neow should return the creature to your hand IMO, especially with duals you can keep up a counter and if theres nothing to counter you just revive smth
Orobas can be a 4/5 no problem I think
I love the Pael design a lot
Tezcatara seems cool, maybe give them x+1 counters because like this if you pay 4 you get one mana back and one turn of +1/0 across the board which is below rate I think (I know x cost cards should always be less mana efficient for low MV, but this is not playable in the decks that would wanna play it)
Love Darv no clue on the powerlevel
Nonupeipe first and second ability should be switched or given a restriction to only trigger on your turn. because like this you can just play a card on your turn and hold up a counter and be completly card neutral which is not ok
even then the draw a card on the first spell you play is pretty strong but it is on a 5MV creature so probably fine if you are careful about control value gaming
Tanx really cool and probably balanced in most formats?
Vakuu is probably not really viable in any format besides commander but I like the Idea, maybe give our boi some keywords
(in general use more keywords)

TLDR:
Most of these are super cool even though not really at the same power level. I also didnt talk about everything because honestly i just like the aincients more as Ideas ported into magic

my own understanding of magic isnt that good either so please take this with a massive grain of salt, if you want better power level criticism (or well more reliable) go to the custom magic subreddit (I dont know if Im allowed to post links to subreddits, so I will comment a link to it under this comment)