skeletonbow: Ok, I literally just finished the game! After all the fanfare and the credits roll up you're deposited back at Kaer Morhen and can continue playing if there are incomplete contracts you'd like to complete or other exploration or whatever. So now that I'm level 35 I decided to go back and visit the archgriffin on that island.
Holy fuck, it is LEVEL 48! I've completed every single main quest and secondary/optional quest in the game except "collect all gwent cards" which I don't know where to go to do that as it doesn't put it on the map and I've been practically everywhere and got all gwent cards I could find/buy/win from everyone.
So I have no idea how you level up to level 48 without using a script or some other hack/mod to auto-level up your character exploiting some hole in the game (such as those that have been publicized in the forums) so I have no idea how you'd go about killing that archgriffin.
I tried lobbing every bomb type at it including superior dragon's dream all to no avail. There must be some trick to it I imagine, but the damned griffin is more powerful than the Wild Hunt! LOL Maybe I need to track down Siskel and Ebert to help me out. er.. I mean Eskel and Lambert... yeah. :)
I have an idea... I could use Axii to tame a bear and get it to follow me onto my boat, travel to the island and axii it off the boat, then go get like 2 dozen more bears and bring them all there, axii them up the mountain to the griffin, then leave them there to battle it out. :)
Wait until nightfall, use a Tawny Owl potion, the Archgriffin decoction and your best Hybrid oil, then strong attack the sucker to death.