In the second level of Rak'Shor Pride, I came across "Poliwen the eternal bone giant" (not even a boss, just rare), probably so called not because it keeps resurrecting, but rather because it's unkillable, at least for me

The problem is that the bone giant has a pretty good set of talents: block, evasion, damage shield, heal, bleeding edge, switch place, etc. On my side, I have a Cornac Bulwark that can deal a massive amount of damage with its shield (in some cases it was over 1000!) but no matter how I attack this bone giant, I only deal a minimal amount of damage. Plus, the giant is more or less always either evading or is shielded, and if I manage to lower its health even a little it just heals all the damage in no time. And it keeps blinding, stunning or dazing me...
I am more or less doing the same (evade, shield, heal, etc.), so we are kind of locked in an eternal fight where none of us is able to deal a decisive blow.
I tried various weapons, to blind it, put its talents on cooldown, stun, daze, etc. to no avail.
Does anybody has any idea on how to put an end to this fight (other than running away or dying)? Any good trick? How did you deal with it?
Thanks.
PS: so far I didn't have too much troubles in the prides (that's my second one after Vor, including the armory although I ran away from the wyrms!). And none of the bone giants I saw until now survived more than a few blows. I am a bit baffled by the sudden increase in difficulty.