I'm probably stupid again but I cant see how you can manage this quest without both the green and blue objective since there is no place in the tower that overlooks all spawn points in a straight line. You must fire twice. There is a 50% chance that you find the blue objective without removing too many objectives ( removing more than four means you have lost). You must make sure that you start by taking out a single spawn point or you will have problems once a Necromancer show up.
A complete failiure is considered if you fire the Dragonsbreath weapon twice but fail to destroy all three spawnpoints! How is that even possible when there is no hit/miss conditions ? Once you fire the weapon all zones from where you stand up to 4 zones away are cleared including the spawn point.
Also, we played quest 1 last week and cant understand why its labeled Hard and 180 minutes. No one in our group came above yellow level and it took about an hour. The "trick" is to disregard the green door and go through the purple vault and in through the left side door to the temple. If you want to involve the green door the labels are probably correct.
You have to move the spawn tokens. You wait for a necromancer to spawn on one of them, kill him, then leave his spawn token where it is and remove one of the others. Now you have two spawn tokens in one zone. Wait for another necromancer to appear there, then do the same trick to move the third spawn token. All three are in the same zone. Use the green objective to destroy all three in one go.
We did it with one shot. Stacked 2 spawns on one side, one on another. Then caught a necro in the blast and elected to remove the far spawn point with his death. Allowing the weapon to destroy his spawn. Boom, one shot, no spawns left.