Nice thoughts.... I liked the "Heist" abillity and "Thor's Hammer" the best - I think the Orb of Lightning is out of place, considering its a Strength based hero (and btw, at lvl 10 it still drains more than half of the mana reserves OO

AND I was able to kill all the Ogres at the top middle (next to the warerfall) and the Dragons camp AND the Golem camp with this spell only (and those are magic immunity... you might wanna do some additional conditions triggers), and still have half Hp... It is a bit overpowered (try using it when only 1 unit is near) + he don't do any animations while channeling the spell - fix those and give it to a warlock, lol, the idea is cool
also, "Underground" should have a longer cooldown, nevertheless longer then the actual duration, so you can't eternally lie beneath the dirt... And I actually don't like the spell that much - u should base it on blink or something, then do some special effect triggers that marks the path of travel or sumtin, but lurking beneath ground and going as you please in such a large scale, only to pop up and stun over and over - that is too powerfull (+annoying to play against, since you can't dispel it, and thier is no counter against it)
Thor's Hammer is great, nothing to pin out, xcept maybe that it should slow targets for 1.5 - 2.5 seconds - that would sing, and make it a good spell for escaping as well as an offensive when launching ranged rushs, giving an edge in game
But overall, this is pretty good, not too flashy, and not too boring, 3.5/5 and that rounds up to 4/5
EDIT: btw. I think she mean the Hero... Dwarven Warrior is not very original, lol