Immortal Dragon — Ruling

Effetto 1

This is an Ignition Effect, which can be activated in the Monster Zone.
Sending a Zombie monster to the Graveyard and this card's Level changing are treated as having happened simultaneously.
If this card no longer exists in the Monster Zone when this effect resolves, the effect is not applied. (You also do not send a Zombie monster from the Deck to the Graveyard.)
When resolving this effect, you need to send a monster, whose Level differs from this card's original Level, to the Graveyard. Furthermore, the sent monster needs to cause this card's Level to change.

This effect is a Trigger Effect, which can be activated in the Graveyard. (It can be activated at the End of the Damage Step, if a Zombie monster in your Monster Zone is destroyed by battle.)