Yes and no. You dont need smart scripts (possibly) and .. mhm...
You would most likely have to make it with phases
And to have phases you need a spell
And to have a spell applied on a player you could use the spell_area table or whats it called.
Example:
If player is in phase 1 and creature is in phase 2, you cant see him.
Then going into the zone gives you the aura that sets you to phase 3, which causes you to see the creature and normal phase (3 = 1+2).
You should be able to limit the spell to be applied on the player when he has the quest.