MISSION 19 - Excavator Fight
After opening the huge metal tunnel gate in the previous mission, jump back in the Batmobile and start speeding along the tunnel. Around the next corner you will need to dodge a few walls that partially block your path by driving up the sides of the tunnel. Shortly afterwards you'll run into and then across a small jump. And then all hell breaks loose as the Arkham Knight reappears in an oscillating death machine.
BOSS: ARKHAM KNIGHT (EXCAVATOR)
You'll begin by facing towards Arkham Knight in his excavator. Immediately throw the Batmobile into reverse and spin the Batmobile around so you can drive away facing forward. The excavator is at least as fast as the Batmobile so you need to move as fast as you can. Ignore the wandering lights that appear behind you, the excavator has no ranged weapons and can only damage you by slamming itself into you (as if that wasn't enough).
As you race along the tunnel, you'll probably notice the Batmobile feels a little sluggish and feels like it slips around a bit more (making it more prone to spinning out), this is usual and requires you to be more careful, especially when turning while driving up walls. A short distance down the tunnel from your starting point you'll encounter a low wall blocking the bottom third of the tunnel. Squeal up the wall to dodge it and trigger the afterburner to rocket down the remaining straight.
Pay close attention to the strange red plugs/ caps circling the wall during the quick scene that follows. These explosives are the only thing that can damage the excavator and you will need to use three in the tunnels ahead to defeat the Arkham Knight. You'll have a brief talk with Alfred here before phase 2 begins.
Objective: Destroy the Arkham Knight's excavator
Once the second phase begins, you will be on the left side of a tunnel complex with your position shown on a map in the bottom right corner. Note the three long tunnels that curve out from the main area to the North, East and South. Each of these has explosives at the end and you'll need to traverse each one with the Arkham Knight on your tail to damage him. It's generally a good idea to travel through each tunnel at least once before attempting to run it with the excavator behind you unless you are very sure of your Batmobile skills.
Preparation: Approach the entrance to one of the tunnels and swivel the Batmobile around (using Battle mode) so that it is facing the tunnel entrance. Then aim the cannon towards the central area where the rumbling excavator noises are coming from. When the excavator enters your line of sight, fire a cannon shell to draw it's attention. Don't take off immediately, wait until the Knight is within a hundred and twenty meters of you before you start down the tunnel (otherwise he likely won't follow you).
North Tunnel: You'll have a medium length jump to begin with (make sure you get up some speed and hit it straight on to cross the gap safely), followed by another medium length jump a few seconds later. The tunnel with then do a sweeping curve around to the right with a third medium jump afterwards (this one can cause problems if you are too close to the wall, make sure to stick to the middle of the tunnel when you round the corner). After that, the tunnel will turn slightly to the right once again and you will blow past the explosives lining the wall to reach a ramp that will jump you back into the central area.
East Tunnel: A second or two into the tunnel, you'll find a set of barriers forcing you up to the left and then back up and onto the right wall. Once you are past them, descend back to the floor of the tunnel and round the corner to the right to see a set of spinning fan blades ahead. Note that there are only two blades here (despite the look) so you should have plenty of space to get through safely. Around another right corner is a triple blade fan. Aim for the gaps as best you can. A second or two afterwards is a second triple blade fan for you to get through, followed by the explosives lining the wall and a jump back to relative safety.
South Tunnel: When you see the debris blocking the right side of the tunnel (a couple of seconds in), drive up the left wall and stay there all the way around the long corner. Once the right side is clear, return to the floor of the tunnel to see a stationary five bladed fan ahead to weave through. After that are the blasting caps and the ramp to safety. This is probably the easiest tunnel overall.
Now that the excavator's health is depleted, you'll see a flashing icon on the map showing where the exit to the tunnels is. Drive through the metal gate to find a grab point in the ceiling overhead. Attach the Power Winch and start pulling down the metal cover overhead. As soon as you do, a rumbling and scene will announce the return of the excavator. When you regain control after the scene, immediately hit and hold AA/ XX to eject from the Batmobile to the safety of the area above. Poor Batmobile, turned into scrap by that monstrous thing.
With the loss of the Batmobile, this mission is over.