Abendroth's Magical Accountant

Abendroth's Magical Accountant is an invisible, shapeless force not unlike an unseen servant; however, the magical accountant is gifted with the single savant ability to add, subtract, multiply, and divide numbers. Not coincidentally, the magical accountant is used as an invaluable aid in summing large columns of figures, collating expense reports, and pursuing any other mathematical challenge put to it while the spell's duration continues. The magical accountant only performs one series of mathematical exercises at a time at the speed of approximately 1 calculation per second. So far, no magical accountant is known to have made a mathematical error; it is assumed they are incapable of doing so.

The magical accountant has just strength enough to record its calculations with a pen on a suitable writing surface; other physical tasks are simply beyond it. It cannot fight, nor can it be killed, but it can be dispelled by taking damage from an area-effect spell, breath weapon, or similar attack.

Note: This version of Abendroth's Magical Accountant originally appeared in the College of Wizardry supplement for Advanced Dungeons & Dragons from TSR. Its use here is for the purposes of providing context for the campaign only.