Loki I/Ikol
Loki II (Kid Loki)
Teller
Mephisto
Dweller
D'spayre
Lurking Unknown
Straw Man
Kkallakku
Nox
Nightmare
Leah II/Hela
Garm
Brün
Thor
There's also a two-page spread featuring Tyr, Volstagg and various others, but that amounts to speculation by old-Loki rather than actual fact.
The Teller wrote all the "scroll" caption boxes throughout the run (basically, it's a proxy for Kieron Gillen!), so there are lots of -VO appearances backdated.
And, yes, this issue establishes that Leah II from "Everything Burns" is a young Hela, sent to the distant past by present-Hela to complete the loop.
Journey Into Mystery #645
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