Heatblast is humanoid. He is made of flame and has rocks all over his body.
Heatblast has the abilities of "pyrokinesis," which is just a fancy word for "fire powers." Ben seems to like the abilities and tends to use Heatblast for them. Although, later, he was "outdated" by Swampfire, but he is still used a lot.
He can also make a "surfboard" of flames to glide on. Although, his fire is occupied to keep him up so he can't use too much of his fire for attack while doing this. Ben claims to have used a flame rock to float on as Heatblast sometimes, making it easier to fly and blast fire at once. Although this was never seen in the orginal series, Ben uses it in Ultimate Alien.