Stun is the most useful part of this skill.
Additionally, each bolt stuns the enemy for a few seconds. It inflicts significant damage and at rank 3 is able to defeat weaker support units with just a single blow. Storm Bolt (1) is the first skill you should choose when you start developing this hero. A high-level Mountain King is able to defeat a few weaker enemies alone. His main statistic is strength, so over time he becomes an extremely tough hero. Most of his skills allow him to stun or slow down enemies, which is very useful and almost impossible to block. It's a very offensive character that focuses on melee combat, although some of his skills may indirectly support your army. It's a dwarf warrior, determined to fight. You will encounter Mountain King at the end of the Human campaign.