Hi.
If my opponent has a immortal creature in slot X, unupped Pandemonium will not affect my own creature in slot X either.
Example:
I place photon as my first card.
Opponent place a photon as well as his first card, and cast Quintessence on it.
I use Pandemonium and nothing happens.
What should happen is that my photon should get one of Pandemonium's effects (thunderbolt, fire bolt, whatever).