I would be inclined to swap the Shield +3 for a Spellguard Shield.
At level 20, anything that can hit you with \~AC22 can probably also hit you at AC25 without much trouble, but having advantage on all of your spell saves and forcing disadvantage on all of your enemy spellcasters will go a LONG way to help avoid all of the random crap that they're likely to throw at you from afar.
Probably useful against those particular enemies:
Helm of Brilliance (very rare, attunement): Resistance to Fire.
Periapt of Proof Against Poison (rare): Immunity to poison damage.
Mace of disruption deals extra damage to fiends and has a chance to instantly destroy them when they drop to 25 hit points or fewer. Granted at level 20 your enemies should be able to beat a DC 15 wis save pretty easily, but if it goes off it's a great table moment.
Change your vorpal blade for a Snicker-Snack.
This is a vorpal blade but it works with charisma for attack roles.
So you have 1 stat needed for max damage
I would be inclined to swap the Shield +3 for a Spellguard Shield. At level 20, anything that can hit you with \~AC22 can probably also hit you at AC25 without much trouble, but having advantage on all of your spell saves and forcing disadvantage on all of your enemy spellcasters will go a LONG way to help avoid all of the random crap that they're likely to throw at you from afar.
That’s not a bad idea, thanks!
Probably useful against those particular enemies: Helm of Brilliance (very rare, attunement): Resistance to Fire. Periapt of Proof Against Poison (rare): Immunity to poison damage.
Great, thanks!
holy water
How could I forget the holy water
Mace of disruption deals extra damage to fiends and has a chance to instantly destroy them when they drop to 25 hit points or fewer. Granted at level 20 your enemies should be able to beat a DC 15 wis save pretty easily, but if it goes off it's a great table moment.
Sunblade
Sunblade is really cool, but the Vorpal Sword is just so good
If the build is flexible it might be better for your concept to take paladin levels and swap the vorpal to a holy avenger
Change your vorpal blade for a Snicker-Snack. This is a vorpal blade but it works with charisma for attack roles. So you have 1 stat needed for max damage
Ring of spell turning is excellent I’d also get some fire resistant armor/potions maybe even some spell tattoos or spell scrolls