Benjamin Olson
Hero
Personally I would hate playing a character so locked in to one repetitive strategy (especially one involving turns of just taking the Dodge action), and I don't think it really pays off at a lot of tables. But it seems to be what the powerbuilders of the land of Theorycraftia love most, and it seems to be working at your table. And the bad news is that most the downsides of such a character came at those lower levels where he had to play a compromised character whose one trick didn't work yet, not at this lofty level where everything seems to have come online for him.
But the big downside now is that he is in third tier play and Spirit Guardians is all he's bringing to the table, as he plods around trying to get into a melee clump with his allies. He now has unbreakable concentration and unbeatable armor, but all he can do with it is 3d8, or 4d8, or 5d8 radiant damage to creatures that get within 15 feet of him.
So let him have his power fantasies a bunch of the time. He built his whole character to do this one boring thing. And accept that you'll never break his concentration (or not often enough to make a difference). Just make sure there are also lots of fights where he can't get within 15 feet of multiple enemies, or where he can't clump up with the other frontliners. Target him for advantaged attacks by minor enemies, hoping for crits and at least making him burn a few casts of Shield, while having the heavy hitters work on his allies to make him burn through resources on healing.
At some point have him fight a pack of skulks. They are invisible, so they will have advantage on all their attacks, and they are immune to radiant damage (in the MToF formulation, they lost this in the MoM revamp). See how Mr. Spirit Guardians likes that.
And have a high level mage Feeblemind him at some point. There's no way he's proficient in Intelligence saves, and I'm going to guess its his dump stat. Even with Luck getting a 17-19 DC without a modifier is a pain. You can beat up on him with Mind Sliver, Mind Whip, and Synaptic static as well.
But the big downside now is that he is in third tier play and Spirit Guardians is all he's bringing to the table, as he plods around trying to get into a melee clump with his allies. He now has unbreakable concentration and unbeatable armor, but all he can do with it is 3d8, or 4d8, or 5d8 radiant damage to creatures that get within 15 feet of him.
So let him have his power fantasies a bunch of the time. He built his whole character to do this one boring thing. And accept that you'll never break his concentration (or not often enough to make a difference). Just make sure there are also lots of fights where he can't get within 15 feet of multiple enemies, or where he can't clump up with the other frontliners. Target him for advantaged attacks by minor enemies, hoping for crits and at least making him burn a few casts of Shield, while having the heavy hitters work on his allies to make him burn through resources on healing.
At some point have him fight a pack of skulks. They are invisible, so they will have advantage on all their attacks, and they are immune to radiant damage (in the MToF formulation, they lost this in the MoM revamp). See how Mr. Spirit Guardians likes that.
And have a high level mage Feeblemind him at some point. There's no way he's proficient in Intelligence saves, and I'm going to guess its his dump stat. Even with Luck getting a 17-19 DC without a modifier is a pain. You can beat up on him with Mind Sliver, Mind Whip, and Synaptic static as well.