MISSION 16 - Defending Ivy's Plants
Objective: Use the Nimbus Power Cell to repair the Batmobile
Now that you have the power cell, you need to leave the airship and somehow get it to the Batmobile. Easier said than done as the Arkham Knight has locked down all exits from the airship. There are two exits (the large circular doors at each end of the room). The one at the far end leading to a pair of unassailable sentry turrets. The other path (near Stagg's container prison) leads back the way you came in, where a Serpent drone is waiting to ambush you.
Take the second option here, as you can use your remote hacking tool to blind the serpent drone, making your escape. Once you are safely outside again, you'll need to glide to the other side of the city above the swirling toxins below. On your way, you will probably get a message from Scarecrow, but you can fly by without paying any heed. When you finally reach the marked rooftop, approach the edge of the building until a prompt appears (LB) to repair the Batmobile.
After a quick chat with Alfred, you'll dive into the glowing orange murk below. When you reach the Batmobile, you'll need to carefully move the LS to slowly drag out the old power cell. All the while, your surroundings will try to distract you from your task.
After removing the cell, you'll get the chance to counter an onrushing victim of the gas before returning to your repairs. Once you begin to push the tube back in, use the LS to force it back into the vehicle. Once the repair is complete, a fairly long scene will play out before you regain control back inside the Batmobile.
Objective: Use the Batmobile's Sonar to locate and release Ivy's plant on Founder's Island
Despite the loss of your map, the objective trail will still display on the road. Begin following it along the road under the noxious clouds until you get close to the area on Founder's Island you need to search. When you reach it, the trail will vanish, and you will need to use your Sonar to begin tracking the roots of the plant.
Work your way towards the center of the cluster of roots and attempt to release the plant (hold in LS) to find out it's buried too deep for you to free from the surface. Alfred will suggest the nearby subway network to get you closer.
Objective: Gain access to the subway network via the elevator at Port Adams to get deep enough underground to release Ivy's plant
Thankfully the your GPS route planner will work again, so follow the trail down the road towards the port. When you arrive at the entrance to the container yard where the elevator is located, Alfred will warn you that Arkham Knight's forces are inside. When the door is lowered, enter battle mode and roll inside.
The area will have scattered inactive drones around, however they pose no threat so don't waste your firepower on them. Instead, focus on the lit up and moving targets throughout the container yard. You'll also be attacked by the flying drones here once again. Remember to use your vulcan gun to bring down their missiles and blast them out of the sky with your cannon. Use your quick thrust movements (LS in a direction + A/ X) to avoid incoming attacks.
In the initial wave, you'll need to bring down nine ground units (diamondbacks and rattlers) as well as two flying drones. If you have unlocked the EMP blast it can be very useful if the enemies are clustered close around you to allow you some breathing room. On the far side of the yard, you'll encounter a heavy missile launcher (similar to the one you took down in mission 13). This dangerous enemy fires a barrage of missiles as well as firing homing missiles at the same time.
You'll need to use the cover in the area as well as your dodge abilities to avoid the barrage, while gunning down the homing missiles with your vulcan gun. Between all this, you should be firing your cannon at the launcher to whittle down it's health. About four direct hits (without upgrades) to the missile turret should blow it to bits. Directly opposite where the launcher was located you'll see a yellow ramp.
Race up it while firing your afterburners to launch yourself into the center of the container yard. Here you'll find even more drones waiting for you. Rattlers, double rattlers and diamondbacks will all be waiting in this central area to blow you apart. There will be fourteen mixed enemy drones scattered throughout the area. Use the tactics from earlier fights in the container yard to bring honour to your clan.
On the far side of the area from where you landed, you'll find the entrance to the elevator. Rip open the metal doors with your Power Winch and then use the same winch to power the elevator (keep the needle inside the orange area as you rev the engine with RT). When the elevator stops, you'll finally be inside the subway.
Objective: Use the Batmobile's Sonar to locate and release Ivy's plant on Founder's Island
Hopefully you learned a trick or two from the Riddler racetracks (if you did them), otherwise some of this may be new to you. There are several sections here where you will need to drive the Batmobile up the walls of the pipe to avoid obstacles/ hazards, so make sure to watch what's ahead carefully. Drive into the first large pipe, swerving past the large yellow construction vehicle. Two walls will half block the tunnel ahead. Weave past the first and then drive up the wall and over the second.
Just past that, you'll reach an area with Arkham Knight banners waving on the roof of the pipe and enemy arrows will begin appearing on your radar. The waiting enemies are behind a metal gate, so you will need to exit the Batmobile (apparently the toxin hasn't descended into the subway yet). Stride towards the door and enter the duct that passes underneath it to get to the other side.
From your position in the duct, you can aim your remote hacking device at the nearby drone to blind it to your presence. Keep in mind that you can only blind one drone at a time in this way. Once the drone cannot see you, stick to the right wall as you advance, keeping an eye on the two drones ahead. The drone at the far end will slowly turn around in a small patrol loop, so be careful about timing your approach to the drone around the corner.
Note: There is a riddler trophy to pick up here if you wish
As soon as you round the corner, blind the drone to avoid being blasted. Wait until the drone at the far end turns away from you before rounding the corner from your hiding place (to avoid being shot in the back when you switch drones) and blind the new drone. Once that drone is taken care of, run towards it. On the way you'll finally see RB prompts overhead, allowing you to swing up on to girders above and safety.
From your new vantage point, you'll see a cluster of drones around a room with the gate switch inside. The good thing is they are all looking away from it, so drop down behind them and simply walk into the room to trigger the switch.
When you do, you should immediately take control of the Batmobile and lay waste to the drones that bullied you earlier. Once your demolition spree is over, press the door switch next to the second metal gate and hop back inside the Batmobile to roll out.
Beyond the gate, you should see a yellow platform that looks like a see-saw. You can probably guess what you need to do with it, but first you need to release the lock holding it in position. Eject out from the Batmobile and grapple up to the small office above to find the controls. Interact with them to unlock the cargo ramp, making it tilt down towards where you parked the Batmobile.
Take remote command of the vehicle and drive it on to the lower area of the ramp. Swap back to Batman and relock the ramp (or not, it stops when it hits the upper area) before driving the Batmobile up and over. This isn't the only one of these you'll need to deal with so remember how it works.
Enter the next pipe and round the corner to find another one of those pipe blocking walls that you need to drive up the walls to avoid. A short distance past that, the floor of the pipe has been destroyed, so you will need to drive up the wall to bypass it safely. Follow the pipe onwards until you find a larger area with another see-saw, I mean cargo ramp.
Grapple across the gap to the office where the ramp controls are. Unlock the ramp to have it drop down, then take command of the Batmobile, driving it up onto the ramp. This one is a bit trickier than the last. The idea is to stop the Batmobile slightly along the side away from the gap so the ramp tilts up. But not so far back that the ramp drops all the way down to a 45 degree angle. When you position the ramp correctly, quickly lock it in place.
Note: There is a Riddler trophy to pick up off the office roof if you wish
Now the ramp is in position, take control of the Batmobile, fire your afterburner and launch yourself across the gap. Nothing stands between you and Ivy's plant now except a short corridor and a wooden wall. Blast away the flimsy wall to find the center of the cluster of roots just beyond. Position the Batmobile in the center and hold down the sonar button to release Ivy's plant and take the express route back to the surface.
I hope you managed to charge up your secondary weapons against the enemies in the subway, as you are about to be swarmed by forty drones of various types. Yes, forty. You read that right. Similar to your earlier drone encounter, you will be supported by Ivy as long as you remain near the church. Use the same tried and tested strategies from before:
Use your secondary weapons, quick evasion (LS + A/ X), stick close to Ivy's plant) to crush the opposition, sometimes literally. After the fight finally draws to a close, you'll receive a video transmission from an exasperated Arkham Knight as the mission ends. Now it's time to deal with the flood of toxin. The Cloud Burst Tank.