said by avalanch:The ashes of alar drop from Kael'Thas and not Alar himself which is kind of funky when you think about it.
Ashes of Al'ar drop from the phoenix boss named Al'ar in the big central room with a huge crystal jutting into the room from the ceiling. And you are right it is in the "tempest keep" however Tempest Keep has several different entrances. Al'ar is in The Eye.
"Second, there are a few that drop from raid bosses. They are extremely rare drops, such as the Ashes of A'lar off of Kael'Thas in Tempest Keep"