Krak is on the Aviak faction. After reading previous posts here, and on the Aviak faction page, I did an experiment using illusion potions to determine which races would be able to sell/buy from Krak. Listed below are con values for the various races. I used a nearby aviak rook as the mob that I conned because merchants will never con below Dubious.
I have a half-elf agnostic bard that I used for this experiment. She has never killed any aviaks (in any zone).
The following races con the aviak as Dubious:
half-elf, earth elemental, fairy, kobold, Guktan (the playable race), froglok (the mob/NPC race), goblin, skeleton, gnome, vah shir, dark elf, barbarian, human
The following races con the aviak as Apprehensive:
wood elf, halfling
The following races con the aviak as Indifferent:
dwarf, iksar, erudite
The following races con the aviak as Threateningly: (I also conned Krak himself while assuming these illusions. As expected for a merchant, Krak conned Dubious)
ogre, troll
When I get a chance, I'll whip up some high elf illusion potions and try out that race as well.
-- Ainulindalex, 71 Half-Elf Bard of Povar (formerly Quellious)

Axe
Backpack
Bandages
Dagger
Hand Drum
Horn
Lockpicks
Long Sword
Lute
Scimitar
Spear
Throwing Knife
Wooden Flute
