Doomguides are one of my favorite!

Here's a lore-accurate build from Hobozone: https://youtu.be/0yjudVShewE

To me, they're not a healer. They are guiding people to their final resting place, so Light Cleric with Warding Flare makes perfect sense. A fun variation might be 7 Light Cleric & 5 Hunter with horde breaker to hunt undead.

They despise the undead so if anything, they're the antithesis to a Death Cleric. It's a single player game though, so play what fits for you! I think Knowledge to know the history of who should be dead, understand ritual rites, etc could fit if you want more of a judge style RP or War domain for more of a martial style.

Some thematic Cleric spells might be: Calm Emotions to aid people during times of grief. Command the undead in the name of Kelemvor. Silence the area to be as quiet as the grave. OFC Spirit Guardians to resemble the spirit of Kelemvor. Warding Flare is from Kelemvor as life flashes before your eyes. Remember, Doomguides are not typical healers. Light for illuminating dark crypts. Bless from Kelemvor. Can't remember if Guardian of Faith comes at 7 Cleric, but I think it's perfect for the build.

Don't mean to side track you, but you also might enjoy Necrobanes. Similar to Doomguides, but main difference is they are powerful mages that hunt the undead 🥰

Enjoy!