I am creating a couple of thematically grouped spells, and I am having trouble finding spells that relate to entropy.
I am looking for spells that make targets weaker and lowering their defenses. They also should be 1st to 4th level and if possible use relatively easy mechanics that are easy to track and remember.
So far I have:
Cause Fear
Sleep
Ray of Enfeeblement
Hold Person
Ray of Exhaustion
Bestow Curse
Inflict Pain
Touch of Fatigue, Chill Touch, Ray of Sickening, Touch of Idiocy, Ghoul Touch, Sands of Time, Excruciating Deformation, Crushing Despair, Overwhelming Grief, Terrible Remorse, Enervation, Calcific Touch.
That's just off a brief glance through Enchantment, Necromancy, and Transmutation spells on the Sorcerer/Wizard spell list.
The shadow caller archetype for fetchling summoner alters your summoning list. Their Summon Monster IV list includes shadows (shocking! I know). The touch attacks do strength damage. That is 1d6 damage per attack that can occur for however many ever turns the summoning lasts and the enemies have to deal with an incorperal undead. Plus, it can actually kill the opponent. Heck, it can even create more spawn. Start a bit of a plague of strength damage.
Not sure if this will help you out too much though. Obviously this idea is restricted to only one build, and I doubt the summoner has that many debuffs to help it. Still, this could be a nice choice for a thematic party.