This guy was pretty easy, I just soloed him as a lvl 50 SMN.
Brought in 3 Yag Drinks and 2 Hi-Ethers, it was lightningsday, so I started with Ramuh, and just had him tank the Dark Elf until I was down to around 100 MP. Once I hit 100 MP, I used my last Drink, started using Ifrit, and used Astral Flow, after 3 Infernos, for 814 damage each, he went down.
He did tear through my avatars pretty quick though, but Dimensional Death seemed pretty random it did as low as 23 damage, and topped at around 130. Also, it makes you feel really superior when there's other players there under level 20 watching in awe as you fight this thing >_>