On PC (there really should be separate sections/threads for each platform)
Since Patch 3 the extra attack skill doesn't end. Any character or mob that has the ability can just wipe out the opposing group. For example, I was in the githyanki creche after talking to Vlaakith. They had all turned against me and I was fighting my way out. Because my initiative is so high and I have a ranged build I went first and just positioned myself in the middle of the room and shot everyone in the room until they were all dead. They never even got an attack off. I even started a new play through to wait while this was patched but even Commander Zhalk on the nautiloid has the extra attack skill and kills the mind flayer in one go so that was a bust.
I submitted a bug report already for it but I haven't seen anyone else mention it happening on their play through yet.
