Gentlexirs: gimme some advice on how to make a vaguely min-maxed Cleric feel a bit more scared/threatened without coming across as Rocks Fall On Your Head-tier lazy DM punishment. I'm running some Ravenloft and been enjoying that almost every character is squishy and feeling the heat but the one dude just has absurd AC and spell buffs going that at times I feel like is actively hurting his enjoyment of the game because most shit cannot hit him and he's doing so much damage that other PCs feel like side-kicks. The flip side is that if I crank shit up, it can feel too excessive on the rest of the party.
In the past I've tossed saving-throw based attacks/spells at people in similar situations with mixed results and I have seen Banshees used quite effectively but I am just seeking some general tips from veteran DMs who can advise as to how to put the fear of the Morninglord back into his heart instead of power-gaming/sleep-walking through every combat encounter. It doesn't have to even by a pure by-the-book solution either, more than happy to homebrew or mix-match as well.