Scroll of Slayer's Insight; best area?

Haven't paid much attention to scrolls, never seemed worthwhile to me since they were introduced after I reached level 20. But I got this one from a drop (gain 250% XP from combat, ends if party fails to kill boss for 5 minutes) so I might aswell use it with a few guild members who aren't lvl 20 yet.

Anybody recommend an area that has a good concentration of bosses and with enemies that will still provide XP for lvl 15-19?

Thanks.

I dont know of many places for characters below lvl 20, and I'm not sure how far you have gotten in the game. But IMO perdition rock is the best place for bosses. There is one around nearly every corner. I killed about 8 of them in about 20 minutes with henchies when I was elite skill hunting. Again not good for under lvl 20's but good for urself if you need to get your attribute refunds up

I've completed all the missions and visited all towns, but I'm restricted to areas the lower level members have been, so Perdition Rock wouldn't be an option. I'll keep that in mind when I'm looking for skill points tho, thanks.

Somewhere pre-Crystal Desert would be ideal...

I got one drop for me last night while doing Abaddon's Mouth Mission.
Also had one drop before, while I was doing the "Final Blow" quest on the Perdition Rock.

I don't know if it is purely coincidental where they drop but it seems to me that the Ring of Fire is the place they show up the most.