@knighthawk What. A what and a what?
I included the links in their names, but basically:
a tiefling is someone with demon blood,
a hexblade is a fighter version of the witch or warlock
a thayan knight is a knight who specializes in protecting a
red wizard of thaya red wizard of thay is a wizard to specializes in a type of magic beyond normal focus of one field of magic over others. Like the difference between a solider who likes rifles more than other guns and a sniper. Except its fields of magic like divination or necromancy.
Like I said, a lot of that is optimal, but not required.