See also Path of Conjuring in the source book.

Although the players can be assumed to act in good faith, they will also want to get creative with their powers. This should be encouraged because it leads to interesting gameplay. To shorten interruptions of gameplay by discussions about what can and cannot be done with the Path of Conjuring, this document hopes to provide some guidelines that can later be referred to.

Conjuring can only create one countable object at a time. Creation of uncountable substances is the realm of alchemy.

The text for the Path of Alchemy from Blood Magic: Secrets of Thaumaturgy recommends the following limitation for stuff created with either Alchemy or Conjuration:

Transmutations create Hermetic “ideals”, rather than perfect real-world resources, which cannot be broken down into lesser constructs. A hunk of hold is a hunk of gold - an attempt to cast coins with it will reduce the hunk to a pile of inert sludge. Before you ask - yes, this means your Tremere anarach will not be able to create nuclear bombs by turning the prince's shoes into uranium. There's nothing wrong with converting lead into gold and selling that hunk of gold to someone else, however - caveat emptor!

Without this rule a conjurer could occassionaly spend a few blood to make their weight in real gold and inconspicuously sell small pieces of it over a large period, essentially raising their Resources background by several dots. With this rule, the conjurer is limited in how much fake gold they can practically sell, because at some point it will be discovered and angry buyers might cause trouble or at the very least not be fooled again.

Small pieces separated from an object within their intended use, such as bullets from a gun or CO2 from a fire extinguisher, will stay in existence until the end of the turn. This means if they manage to achieve their goal within that turn, they will be effective. Note that a fire that cannot be extinguished in a single turn might just spread again to a previously extinguished area.

Removing the clip from the gun to use in another gun or removing the cone from the fire extinguisher to use as a funnel, does not fall within the intended use of the conjured object so disintegrates into sludge directly.

Since the conjured object cannot be split into multiple pieces, this should also apply on the molecular level. This means any chemical reactions, e.g. burning and acidity, will either do nothing or reduce it to inert sludge. On the other hand, using conjured objects in a chemical setup in a way that does not alter them is fine, for example glass beakers and rubber tubes.

Internal chemistry that falls within the intended use of the conjured object does work. This can mean the engine of a chainsaw but also the explosion of a grenade.

Extinguishing fires will work if the method is based on the removal/displacement of oxygen.

The book limits the size of conjured objects to that of the conjurer. This should apply to both mass and volume, but not necessarily length. This lets the conjurer create a ladder taller than themselves, so long as its mass and volume do not exceed their own. Conjured objects appear in or at the hands of the conjurer. Very long objects will appear rolled/coiled up. Use common sense to determine what is reasonable. Unreasonable creations should be not forbidden OOC but rather create a mishap or unwanted result IC, this fits well with the “wild magic” theme of Thaumaturgy in general. A conjurer could create a roll of spidersilk rope, but not a straight piece of copper wire to shortcircuit a powerline 100 meters away. An attempt to create a narrow and very long titanium ladder might result in it appearing neatly rolled up.

Conjured objects are created at ambient temperature and pressure but some variation is possible. Creating a block of ice is fine, creating a block of frozen helium is not. When the object starts to melt, it turns into inert sludge instead of the expected liquid.

Above all else common sense should apply and anything that is absurd should fail. Antimatter? Quark–gluon plasma? No. Go away. A conjurer trying to find the limits of their power may be discouraged IC by having their attempt blow up in their face, literally.