detecting necrotic cysts and necrotic tumors

[Segev]

Necrotic Cysts are instantaneous, so those two won't work. They can detect the Necrotic Tumor spells on the leaders though if they're viewed with Detect Magic active (or some other way to see magic), which should prompt the clerics to look closely for Necrotic Cysts and other asssorted shenanigans.
Necrotic Tumor can be dispelled normally, but Necrotic Cysts require a DC 20 heal check to remove.

Makes sense; I was AFB so running off of memory.

Still, Detect Undead should be able to spot them.

You could also have a member of the clergy, in his study of them and realization he has one, take the Mother Cyst feat by accidentally metastisizing his implated Cyst. This would give him access to Necrotic Awareness, the 1st level spell in the chain, which explicitly detects Necrotic Cysts.

Spellcraft should also still work, if you use the DC for determining what spell was cast by observing its effects after the fact.