Clerical Work: Specialty Priests of Beshaba for D&D 5th Edition

I'm importing the idea of Specialty Priests and channeling a bit of DnD 4E by treating them as Feats.

Specialty Priests of Beshaba

Doomaster Feat


Prerequisite: Cleric with Trickery Divine Domain


You have 3 doom points. As a reaction, whenever a creature within 30 feet of you makes an attack roll, an ability check, or a saving throw, you can spend a doom point to give target creature disadvantage.

You regain your expended doom points when you finish a long rest.