These are the results of my tests to see if it is possible to die while using the spell Globe of Invulnerability.
Poison and Cuts:
No HP is lost, although resting and running is still interrupted each round.
Potion of Detonations:
Heavy stun and mortal wound; no damage.
Potion of Ruination:
Permanent loss to all stats, no damage.
Potion of Death:
A feeling of death runs through your body. No effect.
Crown of Morgoth:
Death while invulnerable. Nice way to prevent people from stealing your crown. ;)