This spell creates a wonderful solvent. It requires a vessel to be cast, which is chosen by the caster. The caster must be touching the vessel as they cast the spell.
The solvent is clear and colorless and appears instantly. It has no smell and has the same viscosity as water. The summoned volume is enough to exactly fill the provided vessel to the lip (or no more than could currently fit inside the body of the caster, whichever volume is smaller*)
This solvent will dissolve any solid thing of a different material than the provided vessel the instant it contacts it, releasing a warm mist into the air as it vanishes. It has no effect on liquids or gases of any kind. Vulnerable materials are destroyed in an instant, there is no splashing or resistance.
"material" is defined broadly e.g. if summoned into a wooden bowl the solvent will dissolve anything not made of any wood (not just the exact same wood as the bowl), and if summoned into the caster's mouth it will not harm any human flesh or body parts (not just the casters).
The damage caused by the solvent is smooth like polished stone, marbles, or the holes in cheese. Any bodies harmed are left like the missing parts were long ago amputated, or never even there.**
The solvent exists for one turn for every level of the caster, or until it contacts a vulnerable material. When the solvent contacts a vulnerable material it will destroy an amount of those materials exactly equal to the volume of solvent. The solvent vanishes as it dissolves a material.
A fine dust is left, a volume equal to what was dissolved. This dust weighs about as much as flour and is a dull mix of the colors of what was ruined. The dust has no value on its own.
The dust, if saved, can be later formed into a paste that can restore the damage done by the solvent.
To form this paste one must mix the dust with a solution. The amount of solution required is equal to the volume of acid that first created the dust. The solution is made of distilled water and a fingernail-sized portion of the same kind of material the solvent originally dissolved.
The solution is created by submerging the sample portion of the material in the water for one full day.
If the dust is mixed with any other liquid it forms an ugly mud that soon crumbles into nothing. If too much water is used a useless slurry is formed, which dries to a dull powder. If the solution is allowed to steep for too long the restored portions will be brittle (and break into fragments easily), and if steeped for too short the restored portions will be soft (and will slowly melt).
The paste is inert until applied (like cake frosting or brick mortar) to where the damage was done. The paste then bubbles and froths for one turn, enlarging like a loaf of bread. The form then shrinks and settles, the object restored to as it was before. (whole objects begin to reconstitute as soon as the paste is correctly made)
Any once living things are whole and alive, and once missing parts of creatures are reattached and fully functional without scarring. All is left as if the solvent never touched it.***
*the human stomach can hold at most about four liters, for what that's worth
**this causes no damage or pain, at least directly. it could leave something very uncomfortable, or even biologically unviable****. whole creatures consumed by it are not killed, only suspended.
***If a significant amount of the dust was lost the restoration of the paste is similarly lessened. If the incorrect paste is applied to something damaged by the solvent these once discrete things are then united as one, but a non-functional melange is created.
****if the particular damage caused by the solvent would be enough to instantly kill a living thing too large to be fully dissolved (e.g. dissolving the heart or brain), the remaining body is neither dead or alive. It is left somewhat incorruptible until restored, remaining tepid and whole unless directly attacked by another or harmed by the environment. Parts of whole things "cut off" by the solvent are also preserved this way, and must be properly reattached by hand when the paste is applied.