Maybe Im confusing Atrocitus with someone else, thought he was more powerful than Larfleeze and Sinestro and Hal Jordan for some reason.
Usually I feel Loki is underhyped on this site. And I feel like most high level lantern characters would split or actually edge out the majority on loki, unless he just mindrapes or has something up his sleeve. Being able to instantaneously construct things that can hang with beings like Supes and Thor even if not for long is enough to give Loki a physical beatdown.
If Loki doesent either end the fight in the first few seconds, mind **** him, or incapacitate him somehow with magic, he cant win physically, but hes got great durability and he can hang long enough to do something.
Bout to inform myself on atrovitus more and come back.