I think its got too much Stunning for level 10.
The RAW level 18 might have too much for 18, lowering its level while keeping its ability to stunlock most of the party is just brutal.
Let Frightful Presence Stun, but change the Interrupt and the BW to Dazed and it should be ok.
As an aside what madman decided Blast 9 was a good idea (or blast 20 for the Runescribed!) when all other Dragons get Blast 5?