Berserker RPG

This modpack includes everything you'd need for an RPG adventure as a Berserker (or other classes, but Berserker was the main focus). There's auto-leveling to level up mobs, Simply Skills to level up your player, and tons of Berserker-appropriate armor in the game to look the part too.

The auto-leveling mobs means no matter what, there will be a challenge to face somewhere in the world. 

The world has tons of mobs, bosses, and structures to explore too.