As two actions, you can create this vial of with a spike ball suspended in it. As an action, a creature can throw the vial at a point within 5 meters, shattering it on impact. The area in a sphere centered on that point twists and sprouts hard spikes and thorns. The area becomes difficult terrain for the duration. When a creature moves into or within the area, it takes 1d4 piercing damage for every meter it travels.
The transformation of the ground is camouflaged to look natural. Any creature that can’t see the area at the time the transformation must make a Perception check against your alchemical save DC to recognize the terrain as hazardous before entering it.
You can increase the damage by 1d4 for each additional catalyst expended.