Undead Dragon

I'd love to see an undead dragon for the dark barracks, it would only have 3 levels and it would have stats like:
Flying unit
Housing space is 30
Production time 45 minutes
Level 1: cost 1500 DE, 2000 HP, 200 DMG
Level up cost is 50,000 DE
Level 2: cost 2000 DE, 2500 HP, 250 DMG
Level up cost is 80,000 DE
Level 3: cost 2500 DE, 3000 HP, 300 DMG
Yes it would be a beast but the cost of DE, training time and housing space per Undead Dragon would help offset the monstrosity of an army made of them.

What is the benefit of this troop over a regular dragon?

Edit: besides being slightly stronger of course