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

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

Specialty Priests of Illmater

Painbearer Feat
Prerequisite: Cleric with Life Divine Domain

• You have a +1 bonus to Constitution saving throws.

• You have proficiency in Constitution ability checks.

• You can survive without food and water for a number of tendays equal to your level.  Every three tendays you gain a level of exhaustion.