Retraining Tokens are a service purchasable from the Zen Market each. A Retraining Token can be used to reset a character's ability score, power, paragon path, feat and boon selections. Initial ability score rolls are not reset. Feats can be reset without using a Retraining Token by paying Astral Diamonds instead.
Retraining Tokens stack and can be used only on the character they are purchased on. After rare large patches, free respecs are granted, which function like a retraining token, but do not stack.
A Retraining Token can also be purchased once from Sybella Artis.