The Hero's Path

How and where can I improve my chemistry skill, as they say in the Elven city that I'm not skilled enough for the next training. My chemistry skill is level 4.

The next skill upgrade will be possible in the city of scholars; if you ask around in the stables, you'll find out where it is. But first, you need to significantly increase your skill level, and this can only be done through practice.

She led me to the wyvern lair, and I killed them there. But the next night, they attacked the pasture again.

The raids will stop when the hero in the wyvern cave is killed. If nothing happens after the fight with the hero, it's some kind of bug.