Well, I think our most elegant combination was a tongue-tying hex paired with a butterfinger jinx. But Parvati had a good turn when she cast the Jelly-Legs just at the same time that I tried the knee-reversal. I think hers hit just before mine did because mine seemed to just miss, probably because Finnigan's knees were all wobbly.

Of course, having good aim helps. It doesn't do any good to cast a really nift spell and have it hit the window sashes! I think that was Dunstan's problem. She's got good technique but I doubt she could hit the broad side of the Great Hall!