I already tried Iron Emblem Gaiden which has one in starting group. Also are there any that have a bishop as the Jagen?
Dark Stone has Lyon as the lord, Call of the Armor has a Shaman Armor as the lord, and Phantom King gives you a shaman pretty early, as well as a Pupil in the prologue that can (and should) become a shaman quite quickly. The only Bishop Jagen I can think of is FE6 Reverse Recruitment where Yodel replaces Marcus.
Requiem has a shaman as the main lord if you skip the Lyn Mode equivalent (recommended on second playthrough or if you don’t care about story)
You get a dark mage as one of your two starting lords in Code of the Black Knights
There’s a shaman like three or four chapters into Dream of Five I think?
I think the MC of Isekai Emblem uses dark magic??
Can’t think of anything else off the top of my head
Drums of War has a recruitable one in the very first chapter! I enjoy the game’s diverse cast of classes available super early.
Embers Entwined does. He’s a pretty good dark mage too.
The Morrow’s Golden Country also has one join within a few turns of the first map starting.
An Unexpected Caller has a Druid as the Jagen.
Harold’s big score has a shaman join at the beginning of the second chapter. He is one of the characters that never leave the party.