Warhammer 40k: Space Marine
if you go tot combo controls in pause menu look for the heavy stun
after than go to execute them and spam shoot to over power in melee
This works fine. Also depends on the Nobs. You have regular easy to kill Nobs and I guess the others with more armor and lot more power are 'Ard Boyz, and they're a pain to take down. When you see them coming just spam with grenades and then use Fury if you have it. Fury + Thunder Hammer = none shall survive.
[Edited by hero007, 9/10/2011 8:14:25 AM]
You have to melee 2 or 3 times and then use the stun strike to stun Nobz or anything tougher than a normal ork.
You can always use Fury as well which will make it far more easier to do it.