Put in RPG terms, quite frankly, generally speaking, when a caster is up against an enemy and can't cast (and Jenny and Artemis are, essentially, casters), he or she is protected or dies. I should know, I only play as Wizard types. Out of spells (or prevented from casting), wizards are pretty useless (as, sadly, my current DM seems to have developed a taste for proving. Over and over again. But I digress).
Of course, we'd never go so dark, but the fact is Jenny's and Artemis' main (and possibly only) combat abilities are disabled at the moment. Artemis might have a better shot, but I do think this would work well with Lilly - it could give her one heck of a moral boost to be responsible for saving Jenny once magic fails, and she's quite well-prepared to fight in THIS arena.
The other "easy" option besides Lilly is Lucas, who is quite clearly a fighter type (and would see it as a personal offense from the enemy the fact that he would have removed her ability to banter during the fight) and who Selene might well enlist on such short notice. However, I'm quite hesitant to have her solve every matter; you've given me a LOT of freebies of late and I would not have her steal the show this time. The story deserves better.
Other options would include Hawkins (tends to coincidentally be where he's needed), Hiro (combat capable, knows the Enemy, has a HUGE bone to pick with said Enemy, his machine senses likely can perceive the fight through walls) or even Tiffany.
This, of course, if you wish to use the "someone helps them" option, which I admit I favor due to seeing this in pure RPG terms. If you don't wish to follow that path, the duo could find some way to wait the silence spell out and then proceed to kick ass and take names, but it would be quite difficult for them.
