Rehgar is a support character who posseses an ability set that goes along with his shaman class: he can turn into a spirit wolf, drop totems, and call upon the elements to aid him in battle. He seems to use a fist weapon for his basic physical attack, and I'm certain he'll have a range of fun shaman specialist attacks to go along with that. Frost Shock had better be on the cards! I'll also be interested to see what additional skins he gets--maybe a Thrall makeover, complete with epic braids?
The announcement of Reghar as a hero makes me very sad that Varian isn't a playable hero option. If you've been playing the alpha or watching streams, you may have noticed that heroes with lore connections in their respective franchises often have more personalized banter when they interact on the battlefield. I would love to see what Rehgar and Varian have to say to each other, but it doesn't seem to be on the cards just yet. Here's hoping for the future!