Cainan is a powerful druid and a Child of Winter. He's trying to bring about the end of the world.
The PCs know these things about Cainan: He was a member of the Monks of Perdition, but began studying forbidden magic techniques, was killed, and came back from the dead. He is wanted in Breland for the murders of almost one hundred men, women and children (noncombatants) during the Last War. He is very rich, due to owning a silver mine in the Eldeen Reaches. He is experienced enough as a druid to wild shape into a dire bear form. Lastly, Cainan is ruthless concerning opposition to his goal; to survive the Final Winter.