"I could help," Loki offers. "Me and whoever versus Thor. She'll still win if I'm not cheating, but it'll make it interesting."
Lúthien, do you know how to take a fall? It's inevitable if you're going to be one of 'everybody'.
"All right, so me and Irissë and Findekáno and Tyelcormo versus Thor. Unless Huan wants to play?"
Loki laughs and looks at Thor. "Might approach fair. - Might give you enough safety margin to pull Mjolnir, if Huan's up for it and you come to an agreement on the use of lightning."
"What are your thoughts on the use of lightning?"
"Might constitute cheating," Loki says, "but I'll check." She unpacks the wind song and plays it softly and gets a cute little whirlwind. "Yep, it works."
"I'll allow it," Thor says generously. "To the practice halls! Though we'd better have this bout in the open air."
"Fight until one of us yields?" she suggests.
Thor pulls her hammer, whirls it by its strap, and rises into the air. The sky begins to darken.
If you ask me to explain why this isn't cheating, Loki remarks to assembled Elves and Maia, I really will not have a good explanation.
I can make all the right predictions - she's not casting a spell, she wouldn't have the first idea how to make another hammer like that, it helps too that it thinks she's 'worthy' and won't let 'unworthy' people pick it up - but it's very stupid.
The clouds continue to gather. It looks for a moment like Thor is going to build enough of a storm to throw lightning as her opening strike, but it turns out she's just being dramatic: after another quarter-minute she comes arrowing down out of the darkening sky, clouds roiling in her wake.
She's grinning delightedly the whole time.
His teeth skid off her armour with a metallic screech. She swings the hammer, although from observing their trajectory an argument could be made that the hammer is swinging Thor.