As an action, you can create this acidic oil. As an action, a creature can coat one weapon with the oil to cause it to corrode creatures it hits. For the duration, the weapon deals an extra 1d4 acid damage when it hits.
Alternatively, you can touch a quiver containing arrows or bolts, granting the ammunition pulled from it the same effect. The oil’s effect ends on a piece of ammunition when it hits or misses.
You can increase the damage by 1d4 for each additional catalyst expended and an additional 1d4 for every other additional catalyst expended.