Thorny Vines will damage any monster or spelunker that touches it from any angle for 1 HP, launching them back the opposite direction. As only Spelunkers and Hired Hands have invincibility frames, monsters and other enemies that find themselves on a thorny vine will repeatedly take damage from it until they are off of it or die.
There are a few exceptions to what a Thorny Vine can damage:
- Wearing either Spike Shoes or Spring Shoes negates damage from standing on the vine completely.
- Players wearing Climbing Gloves are immune to the damage of Thorny Vines while climbing on them.
- Mounts do not take any damage from walking on Thorny Vines.
- Some enemies do not take damage from thorny vines, including Mantraps, Mosquitos, and undead enemies such as Skeletons or Jiangshi from Restless Dead Level Feelings.
- Stunned entities also do not take damage while on thorns.
- Although destroying vines can help make certain situations easier, it may be beneficial to keep them around as certain enemies like high health angered NPCs have trouble getting off of them and may die from being repeatedly poked.
- Shopkeepers who get hurt or die from Thorny Vines is not the player's fault, and thus they will not be held accountable by the Shopkeeper's Association and will not accrue additional sin from Shopkeepers succumbing to them.
- The player will still take damage from thorns if they run into them from the wall or ceiling, even with Spike/Spring Shoes or atop a Mount.
- Thorny Vines on the ceiling are especially dangerous over Spikes or other instakill hazards, as touching them will instantly launch the player downward into their doom.
- Players riding a Mount will take no damage from walking on thorns as well as when crouching through a one block gap with thorns on the ceiling.
- If a player desperately needs to retrieve an item from thorns, but does not have the proper footwear and is not willing to sacrifice a bomb to destroy the thorns, they may get pricked by them and use the given invincibility frames to pick up the item.