1. Stand way back from the battle area, like halfway across the area map. Have the imp go invisible.
2. Fly the imp into the battle area. Pick your target. I do 'healers, then wizards, then small fry, then the rest', but other than 'healers first', it really doesn't matter.
3. Sting. This generates a surprise round. Use it to sting again. Note that since your other characters are so far away, they are not drawn into battle.
4. Use Fly/Disengage and the rest of your movement to get to an area out of line-of-sight. Make sure to get far away, outside of the normal movement range of enemies. Crouch (hide). If you are outside of their normal movement range, they will do nothing. If you are inside that range, some will try to get to your position.
5. Next round, move up to an enemy and go invisible. Do not engage - this round is positioning. Enemies do nothing to invisible enemies, even if you are actually in hand-to-hand range. Take an extra round to position yourself next to an enemy if necessary (remember to Fly before invisibility because Fly removes it).
6. Sting.
7. Repeat 4 through 6 until everyone dies.
