This game is very different regarding RPG builds. You have to go in thinking "survival" more than "Kill everything".
You don't get much for killing all mobs in a area nor does it help with grinding, the drops are shit and it takes way too long to plan out "clearing" an area.
The main take away with this game is going in to finish the job you want to do. I am running a Nympho character and I can one shot most enemy's via the sex attacks, and even with that I do quests to finish them, not kill all (unless that's the quest).
I did a small test on the mage build in the beginning and found you have to really know where you are aiming and not to just blind fire like you would with swords or sex attacks. I believe you need to hit the square they are going to move to not what they are on.
think of it as, One monster ok this is how I kill him, five Monsters ... ok need to go around them and try not to aggro them.
This has to be one of the most unique sex games I have ever played, it uses sex as not only an attack but as a punishment for failing, and even if you fail, you can still get out and get back home if you plan it right. During my run I sold Lona to the fish people and became a slave right away, I managed to leave (along with 61 joy waters) get back to town, remove my slave mark, brake out of my cuffs, and start the main quest.
Don't hesitate to hire help, they can be quite useful. Cocona is quite the buddy.