[quote=@DemonMiyu]
[@knighthawk] What. A what and a what?
[/quote]

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 [url=http://forgottenrealms.wikia.com/wiki/Red_Wizards_of_Thay]red wizard of thay[/url]
a 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.