Thief for hide/sneak, cheapshot, some sort of knockout + steal.
Hide/sneak works around the intentional drawback to non-hiding classes that they can't guarantee getting the jump on someone. So maybe you haste yourself with a scroll, sneak up to some bashable person who can't detect hidden, eat an enlarge prep and bash them down.
Invoker you'd knockout, make quicksand around someone not flying, backstab, spam cheapshot. Doesn't webbing also cancel flight? Throw that in the mix for added synergy with cheapshot. You get bash resist from major shields which, as a thief, is nice. Running around with invoker shields makes it less likely you get steamrolled by someone on a missed knockout attempt.
W/ bard you'd hide/sneak up to someone and sing lullaby. The major synergy here would be the ability to steal potions and (possibly) blind via scroll prior to singing nightmare et. al. Guy doesn't get to teleport away and fight the nightmare by himself. He gets to have you there spamming cheapshot or flee/knifing while he fights it.
Air shifter + necro could also be funny. Scout at high-altitude, flyto, revert, c sleep. Or healer/necro for gate/sleep hilarity.