Head through the next couple of rooms by activating the generators on the ground. At the end, you'll be attacked by Ninjas. They have blades so you have to treat them like enemies with knives. In this case, it pays to be aggressive since they all have swords. They shouldn't be too difficult. Make liberal use of strikes and evades. Once they are clear, there is a piece of floor that can be destroyed with explosives. Open detective mode to find it by the projection wall. Blow it open and then use an electrical charge.
Enter Wonder City and walk towards the door in the distance. After you take a better look at the door, examine the different machines to access their video memory. After you've examined a few of the robots, you will be attacked by two ninjas in the middle of the street. After a few more robots, the same thing will happen. But the middle of the street is a relatively safe place for the fight. Use your strikes, counters, dodges and takedowns and you'll end these fights quickly. Once you've examined all of the machines, head towards the big door and just to the left is the secret door. Examine it to find the switch and then you will be attacked. Be ready to counter and when you do, the door will open.
Follow the tunnel and turn and eventually you'll come to a ladder. Climb up and out. Walk forward and follow the light. you'll eventually be lead down some stairs and through a door. Go through the door and do as he says, drink from the chalice.