Whats the best way to get the scrolls?
Here are some general guidelines I like to follow.
As the Champ pops, get his lifebar up so you can tell how much time you have, as well as all protectors and whoever else may be hitting the Champ. I like to stay within screen of all the players as well as opening paperdolls of the characters so I know who is who.
I don't even attempt to Snoop packs until the boss is at least 1/8 HP's or less,it's not worth getting noticed UNLESS you have already been seen and they are onto you. If you've already been seen it's a whole other ball game altogether.
Depending on the veterancy of the spawners, they will know how to make things extremely tough for you, fellow thief. Lots like to Invis a lot before the boss dies, making things difficult. Poison fields and EQ's are your worst enemy, from REDS that is. If you're BLUE, other blues can do whatever they want, eq, poison, meteors, lightning, it won't matter. They can't hit you.
Keep the target bars UP, at all times. If no raid is present, the spawners may linger afterwards. Lots bolt for the gate after the Champ drops, usually protectors.
A good strategy is to get the PROTECTOR'S pack on 'last object'. Head to the starroom before the boss drops. Wait in front of the gate ready to steal, blocking their run path. Open their pack as soon as they run into you. Blocking their path gives you a few extra very precious seconds to check the scrolls out.
Hopefully you'll be heading out of there with a scroll worth a few million.
**Extra tip**
Pick yourself up a pair of old school 'Invisibility Charged Boots'.

Make that steal, slip em on, and disappear instantly. One of my favorite tools of the trade.
Don't leave them on your character and log off, they will revert to normal boots if you do so.
Any questions, just ask. I'll be here all night.