Here are a few random spell guidelines from Ars Magica worked up into spells. First is an effect to communicate with animals, and the second makes alcoholic drinks safer for a short time.
Tongue of the Beasts
Intellego Animal 25 / Creo, R: Eye, D: Concentration, T: Individual
This effect allows caster to understand and communicate with a particular animal. The caster perceives the basic surface thoughts of the creature, and also “speak” directly into the creature’s mind. No words need to be actually spoken while the spell functions.
The Magus must still interpret the perspective of the animal properly to understand it’s motivations, and must also communicate to the animal in terms akin to its own perspective to be properly understood.
(Base 10 to comprehend the surface thoughts, +1 Creo requisite for creation of understanding back to the animal’s mind , +1 for Range to Eye, +1 for Duration to Conc.)
This spell is useful for imparting instructions or information to an animal, which is a mainstay of many myths and legends.
Withhold the Drunkard’s Muse
Muto Aquam 10. R: Touch, D: Sun, T: Individual
This spell changes the contents of a container so it is no longer alcoholic, but otherwise is essentially the same. This means especially excellent wine will will taste excellent, and poor ale will still be undesirable.
At the expiry the contents return to normal, restoring the intoxicating effect. This may cause interesting mishaps and unexpected circumstances if the liquid was recently drunk.
(Base 3 to change liquid into a slightly unnatural form, +1 Range to Touch, +2 Duration to Sun)
This effect could be created as a Perdo spell but it would be is exceptionally high level, based upon the Level 15 guideline of removing the alcoholic property. That is an effect of using Perdo magic for subtle effects rather than destroying all the liquid which would be easier. The final level difference between a spell level 10 and spell level 20 is significant.
Perdo is suitable for effects where the removal of the aspect needs to be permanent, such as removing poison from a liquid. A level 20 spell to neutralise poisons from liquid seems appropriate in terms of spell level and also usage.
A good example of that type of poison removal spell has already been created at the Net Wizard’s Grimoire, called ‘The Deathly Poison Made Safe to Drink‘, with a snappy side-note saying ‘Hadrianus developed this spell so that he could falsely reassure his victim’s that their own cups were safe to drink.’ Nice eh.