Is it 3 fingers and there is a 2 small nails behind the skull.
Is it base from this blizzard icon.
You are always summoned when the trolls subject is discussing.I see what Blazekraze is saying, and I can see the two fingers and fingernails. However I think Panda is right; it's kind of an uncomfortable pose, & the outer finger should be more visible, wrapped around the the left side of the skull. That way it really looks like it's cradling it.
Even in the Troll Regeneration hicon you linked, the fingers are rather far apart.
Other than that looks pretty cool I'd love to use it but I feel like it's a bit fuzzy/lacking in sharp contrasts vs Blizzard icons.