Okay, I've been thinking: How about having one of the keys on Tarsis.
The main hook with this place is the total blanket "no tech" rule.
The idea being that anything you bring fails, so there's no point. They'd also be stuck there until a pre-aranged time or visual signal for the Asgardried to pick them up.
In adition the group would get hit with about every mythalogical creature we haven't yet seen and I really want to do a pitched battle with some of my legions.