D&D 5E (2014) Idea for priests in a temple: (un)holy armour

[Eltab]

"Holy Mage Armor" while walking around a consecrated site? Sure. Maybe a sage of the faiths should warn the PCs first, or describe the special Hallow spell that particular denomination uses. So they know that the guys in robes are tougher to hit than their Wizard.

 

[ZenBear]

Seems legit to me. I might have a high priest performing the lair action far out of reach of the players or somehow protected until they cleave through the lesser foes. Another option though is taking inspiration from Dark Souls 3 Deacons of the Deep boss fight. The Arch Deacon is a spirit that possesses a random lesser priest whenever the one it currently occupies is killed, but every time that happens it takes force damage. Mass defense buffs seem fine, or just a specific buff for whichever Deacon is currently possessed.

 

[Li Shenron]

I really don't grok the idea of priests running around in armour all day, so how about this for when PCs attack:

Lair Action
As a lair action, members of the clergy not wearing armour or carrying a shield gain a bonus to AC equal to their Proficiency bonus.

What do you think? Too powerful?

I think in most cases the resulting AC would be lower that the one for a fully-equipped Cleric, so it certainly wouldn't be too powerful.

But I don't even think you need to define it as an action at all. It could be just a permanent magical effect bestowed by their deity on the whole temple.