Tarhun's philosopher's stone

after placing a live human(s) into the arcane circle an hour is spent for every 120 miles that the arcane circle encompasses. the soul is transferred into a small crimson red stone (liquid stone if only 1-5 souls were transferred.) and available for use until dispelled, upon which the souls are released and returned to the body (If the body is decomposing then it is up to the DM's discretion as to what happens to the humanoid.)

Attempting to use this stone allows the user to avoid using the spell slots equal to the number of souls used to make the stone. If 5 humanoid souls were used to create the stone then the caster could cast a 5th level spell once, or five 1st level spells each. the souls are consumed and material components of spells are not substituted with the stone and must be provided for every spell used.

this spell could be used on a large scale or on one person. Anyone inside the circle upon completion of the spell is trapped in the stone. (creatures warded by protection from good and evil or magic circle spell can't be absorbed by the stone.)