You can also kill Iksar Pariah's/outcasts in Warslik's or Swamp of No Hope in order to raise warrior (
Legion of Cabilis) and Necro (
Brood of Kotiz) guild faction.
I think the only way to raise Shaman (
Scaled Mystics) and SK (
Greenmist) guild factions is through quests (like said
bone chip quest, which raises every faction but Necro)