It's a bit hard to tell from your image, but this review indicates that he re-summoned the Pùca from Season 4.
He’s trying every mystical solution he can find - bringing back a pooka from last season, making Nora’s kid come to the House of Mystery to wish him healthy again, shouting at archangels to cut a deal, something untoward with Ray’s foreskin. As ...
The movie suit:
Bruce: Silica-based quartz and fabric. Abrasion resistant. Heat resistant.
Barry: Uh, yeah, I do competitive ice dancing.
Bruce: It's what they use on the space shuttle to prevent it from burning up on reentry.
Barry: I do... very competitive ice dancing.
-Justice League, 2017
The TV suit is repurposed from a prototype fire-fighter's suit. ...
In the present Arrowverse, they have their own Justice League which consists of
White Canary(Sara Lance)
From L to R: Martian Manhunter, Batwoman, White Canary, Supergirl, Flash, Black Lightning, Superman
This Justice League was formed after the events of Crisis on Infinite Earths when ...
Is it possible you're thinking of Adrian Chase in "Kapiushon", episode 17 of season 5?
Adrian Chase : Cecil Adams. You know him by his street name, The Count.You put arrows in him.
Oliver Queen : He was gonna kill a friend of mine.
Adrian Chase : Felicity Smoak. Yeah.
[puts on Oliver's quiver]
Adrian Chase : Confess or you get the same 3 arrows.
In the D.C. universe they seem to use the word Metahuman instead of Mutant (like the Marvel Universe. The term "metahuman" seems to vary as well. Often times they refer to aliens (like Superman) as having "meta" abilities. However to answer the other part of your question, Sara Lance (White Canary), Ray Palmer (Atom), and Mick Rory (Heat Wave) are not ...
After the events of Crisis on Infinite Earths which was a five-part crossover event of the Arrowverse consisting of the shows:
Legends of Tomorrow
these shows were all made into a single Earth known as Earth Prime making all the shows happen on same Earth. Thus Supergirl is now officialy part of same universe as well as ...