Play on the gnome's greed.

Gnomes. Clever little bastards, but they all suffer from the same innate flaw. Curiosity and greed. Nothing is ever enough. They always want to learn more, make something new, and generally tempt fate at every chance. Gnome alchemists were twice as bad. You decide to apply strategy instead of directly attacking the adventurer with so few HP.

Given your current form, you have a very limited ability to physically manipulate objects. At best you could condense your form into a liquid, but it wouldn't be very much. Perhaps enough to fill one of his vials or-- or... If you had a mouth, you would be grinning with wicked glee right about now. The gnome advanced slowly, and you used this as your opportunity to silently glide beneath the bridge toward the darker end of the cavern. This was your home, after all, and you knew its denizens better than most. The predators around here were some of the nastiest baddies, as far as low-level zones go. You, being the bottom of the food chain and little more than a neutral nuissance amidst your ecosystem, never felt directly threatened by the less-than-friendly monsters that lurk in the dark.

There! You swirl up and hover before an crude, wooden signpost. The signs that littered the small cave network bore various warnings to players. Something of a guide for those new to adventuring life. If you could subvert the intent of these signs, the gnome would never stand a chance. Dusky, white paint sat smeared in all capital letters: "WARNING! BEWARE TREASURE!" Undoubtedly, this sign was to teach players about one of the earliest hazards in any dungeon environment: mimics.

Closer and closer, the gnome is already halfway across the swaying, rope bridge. Cutting the rope would be so much easier, but such is the price one pays for intangibility and flight. Instead you start to whirl your gaseous form into a cyclone, spinning faster and faster until you are little more than a spinning orb of liquid purple, no bigger than a fist. SPLAT! With your final rotation, you spray your liquified form across the sign like a handful of blackberry jam. Before any of you can drip off, the liquid ripples and crawls over the sign face, ruining one word of the warning in white paint. In its place, your liquid body arranges to complete a new message: "WARNING! FREE TREASURE!"

At last the gnome approaches. He holds up a torch to better see the sign, and it takes all of your willpower not to scatter and flee. You really, really hate fire. The mustachio'd alchemist nods to himself and gibbers something in gnomish. A nagging fear weighs on you, and just when you suspect he sees through the gambit, the little bastard actually does a hopping heel click. His shoes pitter patter along, ferrying him forth toward his unwitting doom. After a moment of vibrating your spores back into a vaporous state, you drift along the cave floor like roiling, purple mist, waiting for your chance to strike.