Shadow of the Vaal

Cruel difficulty, I killed all 3 bandits, grouped up with some people and went for Vaal. I clicked in the pyramid but couldn't activate him myself, so someone else did. We lilled him, then I couldn't procceed to Sarn City cause I didn't have the Apex

I think the part that bugs this quest is that if you don't actually go back to Eramir to get the Apex before you kill Vaal, it doesn't allow you to proceed. Now im stuck on act2 with nothing to do... help will be appreciated