I'm nearly certain that Cripple Shot is an evil power only.
And for 500 extra resources, you could just get Thranduil, and normal hero who is enough of a hero killer, so getting an elven one isn't nessecary.
Of course, if you still want one, then it wouldn't hurt to get Archer specialization, and Stealth. Also, putting high power and vision would help you find and kill the heroes.
Summon familiar would uncover stealth heroes as well.
I will open one of my six mouths, and I will sing the song that ends the Earth.
I love you in a totally platonic way Xaph - Jon Rolos | Xaph does mutha****in' win the thread. - Anakin
Xaph, I wish you were my friend IRL - Boba Fettucini
Well I think it's obvious why Peter Noone would care about Xaph - Newt_Gunray
Xaph is suddenly full of win! - Zaarin | Xaph, how often do you win threads? Because you just won this one - Catabre