Firstly a spell stop natural healing for the duration, which makes more sense as a reworking of the Creo Corpus guidelines for wound recovery. In 5e it is easier to inflict a light wound than heal one (base 10 vs 15), so using similar stepping difficulties with Perdo Corpus base 1 causes a -3 to rolls, which scales by additional magnitude to base 10 to cause a -18 modifier. And further to base 15 to stop all wounds from improving for the duration.
Curse of Chronic Injury
Perdo Corpus 15, R: Touch, D: Moon, T: Individual
The target suffers a -9 to all wound recovery rolls for the duration.
(Base 3, +1 Touch, +3 Moon)
The Stagnant Flesh
Perdo Corpus 35, R: Touch, D: Moon, T: Individual
The target cannot heal naturally from any wounds or infliction for the duration. All recovery rolls which indicate an improvement are ignored, and negative side effects of rolls are retained.
Flicking through the Ars Magica spells here and there, there are as many permutations and variations as a player could want. That said, I sometimes find it easier to review a complete variation of a spell for use with a character instead of considering it in my head. There is something more tangible when writing out the summary of terms and mechanics.
Vital Rest for the Incapacitated Custos
Creo Corpus 30, R: Touch, D: Ring, T: Circle
This spell grants the target touched a +18 bonus to all wound recovery rolls made while the spell is in effect, and the target must stay within the circle/ring for the duration. Note that the spell will cause warping.
This variant is intended for custos who require critical intervention and will not be moved.
(Base 15, +1 Touch, +2 Ring)
A variant spell for healing a group of critically injured people, with this version using the highest spell guideline from the core rules and reworked to last as long as needed. I can see this being used when an important character suffers a dire wound and they must be cared for straight away. An incapacitated character could be placed within the magic circle to ensure their rest and recovery is optimal.