I would suggest Outsider
Nasty looking one.
I would suggest that the Ulgan be made an extraplanar equivalent of a dinosaur, maybe even Infernal. There could be herds of them hunting across the fiery wastes, snapping up stray petitioners and fiends.
As for strange powers, it could have some psionic power, or perhaps some strange movement ability (blink tyrannosaurs!). Maybe it is able to stretch itself like Elastic Man.
It could be the infernal version of a Leucrotta, luring stray planewalkers with cries for help, and then ripping them open like a Deinonychus.
I do, however, approve of the Druidic dragon idea. This one just seems too streamlined and simple to be a true dragon.
Devon