The Foster's Effect was an magic reaction discovered and calculated by Dr. Foster quite some time back. When Dr. Starfinder and the students on Weirdsister College teleport a Australian woman (Supposed to be Foster's assistant), they try to build a device that can find a way around The Foster's Effect. It is later revealed that the Australian woman is in fact Dr. Foster. The Foster's Effect can happen when casting too many spells. With all that energy flying around at the same time, magical paths cross over and cause something known as The Foster's Effect. This reaction causes spells to multiply out of control, and has created all sorts of natural disasters. Using magic for selfish and trivial ends can also cause The Foster's Effect.  Misgone Magic was what they used to call The Foster's Effect in the Middle Ages.

When Miss Cackle teaches her students about the Foster's Effect, she tells them a rhyme about Dr Foster trying to stop the rain, but ending up in a bottomless puddle instead. This is based on an old rhyme: 'Dr Foster went to Gloucester, In a shower of rain, She stepped in a puddle, right up to her middle, and never went there again.' Miss Cackle refers to the rhyme in spells class, saying that Foster's use of magic caused the giant puddle.