One of the scheduled, must-do quests is to help the castle guard fight a griffin. It’s the only guaranteed griffin battle in the game.
We accidentally killed it right away. I mean, that’s awesome usually! OP fight. But I’m trying to pursue all of the story. By ending the griffin I cut the quest short. An entire corner of the map is avoided, a marvelous, cinematic griffin battle is missed, and another portcrystal is temporarily unavailable. And that dude we helped retrieve the grimoire, he comes in with his book and fights with you. It’s really useful to have another combatant at the top of the tower.
I thought about trying to reload and redo, but the save system is too auto-generated. Besides, I killed it on one go! Yay!