I’m maxed out on Lvl 40 and keep getting wiped out by Lord Cranbourgh when he leeches me of both stamina & mana. I have been grinding for a while trying to get enough mana potions but I can’t seem to get enemies to drop them or if I do get the occasional mana potion it is a minor potion which will not really make a difference. Is there a way to find more mana?
Higher luck will get you more and better loot, so even if you don't find enough potions, you will be able to buy some by selling the extra stuff.
To avoid getting drained, use ranged attacks like Firebolt II, or a good bow with high ranged skill. With enough practise, you'll get the cost of spells down to 1 mana, freeing up skillpoints for other things than magic.