This fight is beyond easy, go in with a RDM/BLM - WHM/BLM or BLM/WHM and x5 DD's and this fight is easy.
Warriors and Dragoons excel here because of Angon and Tomahawk which will cripple the Flans defense so much that it's easy to zerg-rush him.
If silence does not stick then you are in trouble, bring a DRK for security.