Down on Skid Row

To Flint: You notice--on the desk above the sprinkler system, a bottle has been knocked over and is dripping into an intake tube on the system.

To everyone: Important to note: the kids under the table aren't in any state of dissolving.

For the first time in the mutant plant's brief sentience, it learns pain. Flint's slab of fist slams into the vine, causing a deep indentation to form, oozing liquid down the length of its shape. The head, in response, throws itself back and then violently jerks forward, shooting a spiny barb from within its "mouth."

Spine Attack: 15+3=18 (hit)
Damage: 1d6+5 (11) plus Poison
Fort DC 13 or 2 Dex Damage

In addition, the head manages to inch itself 5 feet closer to the fray.