Getting poisoned by the Queen Endrega is pretty much a death sentence. It comes out quickly in a spray and hits you even if you're trying to roll out of the way.
Even if I'm able to kill the other Endregas around her (which re-spawn if you save after killing them…at least I can farm experience this way), fighting the Queen one-on-one is futile and suicidal.
Which signs and strategies are especially effective?
Is it just another matter of having to have a perfect run to win the battle?
Best Answer
I just killed my first Endrega Queen (I find out we have to kill two of the things. TWO!), and if you're getting hit by the poison, you're probably fighting much too close to the queen.
Hit and run tactics are your best friend here -- the greater distance you are to begin with, the easier it is to dodge the poison stream, the charge attack, everything.
The other useful thing was the Aard sign. The damage / daze effect it creates can stop most of the Queen's attacks mid-animation, giving you time to get in a swing or two. Dart in, blast her with the sign, strike a few times with your sword, dodge away, wait for vigor to recharge, and repeat.
I found that when fighting the queen, the quick attack style oftentimes did "minimal damage", so stick to heavy attacks when you can.
The last helpful advice I can give is that the Queen shakes her head just before spraying the poison, and rears back before her charge attack.