Don't forget you can get a mage focus item with reclaim energy clicky. This also turns your pet into an emergency mana battery.
Example:
http://wiki.project1999.com/Shovel_Of_Ponz_Quest
Even the level 30 pet will return ya something like 120 mana. That's enough for another engulfing + fear to finish a mob off or 2 lifedraws for roughly 90hp in healing or enough mana to be able to feign if you weren't paying attention and went LOM & got into a bad spot.