I had this revelation that I would love to have a FP Heal, so I can 100% allocate my flasks to FP, but it was so much damn Faith just for some super slow healing spells... so I went back to super high INT, Mind, and Vig, and slowly adding to endurance and dex.

I used the seal a bit for the healing spell but never used it for offense. Admittedly, there are some super cool Incants late game, like the dragon lightning. But I just think it looks pretty badass to have the Rennala staff and nothing else. I know when I get summoned people must be like oh here we go a mage to hide in a corner, but im pretty aggressive. I love co-op bc I will take aggro away, and dodge to survive, then when boss aggro's them I pummel with Moons. Rinse and repeat.

Edit: By the way, did you go find the Ranni Dark Moon spell? Since we use the same staff, you should go use that. Its the best spell in the game for this staff. it absolutely obliterates people, one shots everything, even strong guys. I use Talismans for faster casting, so the weakness is really just time, but if you move a lot and create space its not that big of a deal.