These poison assignments are based on which classes can (and should) be specced to buff specific type(s) of poisons for raid.
RED: Everybody should be using Exemplar or at least Gnostic Hemotoxin for raids
BLUE:
Swashy: Savant's Turgur
All others: Savant's Ignorant Bliss
PURPLE:
Assassin: Savant's Warding Ebb or whichever is missing due to absent class
Brigand: Savant's Warding Ebb
Ranger: Savant's Cerebral Ebb
Swashy: Savant's Enfeebling