Skills for an Inferno hero.

Storm Lord is indeed a weak ability, but Ice Lord is quite good. As I mentioned above, it's enough to take the basic Chaos abilities and one of the lords, and that's it. You can ignore the rest. The exception is if you're playing as Groll, then you can take Blazing Wrath or something else.

Storm Lord is weak, but it's still a direct path to mana depletion, which is very good for poorly defended demons. If the map is small or medium-sized, I think it's worth upgrading Chaos, especially in combination with attack, because you can take Cold Steel (even though it closes the path to Urgash's Call).