Hey!
I used 1 scroll 20mins and 10-0min it stops working and i get no 2x xp..

847xp with slayer .. (banshee gives 770xp + helm)
i used 4 scrolls and 3 times 2x xp stoped at low minutes (10-0min). i used 20min 20min and 40min.

Frost drag gives 1925xp + helm