Currently spigot can do 2 damage events

damage(Double) 
and
damage(Double, Entity)

what I'm proposing is to add a feature were you can add a DamageCause to it

damage(Damage, DamageCause)

This way if said entity were to die from the damage the DamageCause of that death would be whatever you set the DamageCause to.

ex.
Player.damage(20.0, DamageCause)
and the death message would be
'%Player% has been squashed by a falling block'
instead of 
'%Player% has died.'