It is VERY useful, but not very popular due to the mana costs. Quite a few spawning guilds lean on it heavily. Mainly it is the fact to be TRULY useful, you have to cast arcane empowerment to harness the benefits, and that does not last long enough.

As to scrolls, they can be found on most of the named monsters as well as troglodytes, or any ML specific monster.

Hope this helps.