New Dragon Idea - Dark/Shadow/Spirit

My idea was for a new dragon type that adds a passive that isn't necessarily game breaking or even in favor of those ahead, but still adds a nice bonus to the team. My idea is that killing the Dark/Shadow/Spirit drake (it could be a Shadow Isles dragon) would basically make allies explode on death, with the radius and/or damage increasing per drake stack. It's a nice little element of combat that can at least add a bit of sting to tanks who die diving enemy teams, or to ADCs and mages who die in the backlines to those sneaky assassins. Thoughts?