The first time I battled the pinger it wasn't that bad (in daylight), when I got to the terminal Level it wasn't that easy (that's when you're inside the building). The Ceph keep showing up and screwing up my game.
Seems that the AI is conditioned to releasing more Ceph when the Pinger has taken a certain amounts of damage (when you see the red "bulb" shooting out sparks expect more). If you haven't figured it out already the way to take the pinger down is to shoot the red dangling "bulb" thing at it's back (update: not sure if you need to do that)
1. Releases EMP ball which brings down your shield
2. Fires his weapon
3. Some other weird thing
When he shows up (burst through the wall in the Terminal Level) cloak and hide somewhere, if you have the sniper rifle take down the few Ceph buddies that come with him without giving away your position. Line up your shot, uncloak, Fire, cloak. Repeat. This way when you fire your energy isn't all gone. Now that those fools are gone you can make sure you have the heavy weapons, first gather some of the JAW missile launcher (rocket launcher). On Xbox 360 just hit "up" on the D-pad to go into Tac assessment mode, it will highlight where all the weapons are. Make note of the "swarmer" weapon which for the terminal level is shown on the Tac as "acquire".
Once you have the Rocket Launcher (JAW) go ahead and sneak behind him from the second level. Hopefully at this point he's still distracted with the marines. Stay cloaked, line up a shot, uncloak, Fire, cloak again, and hide. If he's still distracted, do this again to launch off shots with as many rocket launcher as you can find.
Get to know the area because it's going to be important for your survival. The problem with fighting the pinger is that you don't have your suit energy to use which you've relied on for most of the game. There's an area, a small room on the opposite end of the wall which he broke through, that is a great hide out when you get over-whelmed. It's great because unlike most of the walls on the second floor and around the wall here can't be destroyed.
Using your MAP will be really really important here. You need to know what the pinger is up to before you attack, you don't want him to see you because he's really stubborn and will keep attacking you incessantly (annoyingly) making it hard to escape or let off any shots without dying. At some point (when the pinger has taken a certain amount of damage) the bigger Ceph guy will come around. (you know the guy who glows red and gives you 300 nano-catalyst to collect) He's like the Golden Elite covenant from the Halo world. I died many times trying to fight him (even on easy) while fighting the pinger. I found the best way to deal with these guys is to wait for them to come to you. Hide in the room at the end of the building I talked about. When the big guy is coming throw some C4 at him and hit the button. There's no time to be distracted with that idiot when you have the pinger to deal with. Just take him out quick with the C4 and get it over with. For the other guys, let them come to the room, let off a shot gun shot when they turn the corner and go into armor mode, then melee them rapidly and they go down quick (might not work on hard difficulty).
Once you take care of them it's back to the pinger, wait for him to fire that energy ball, let your suit energy charge up, go into cloak mode and dash away from where he shot the ball. Hide somewhere. If you're out of the Rocket Launchers (JAW) use the swarmer. But be warned, the swarmer is heavy and makes it easy for you to die since you can't move around with it as fast. You can also try using the swarmer first while the pinger is still distracted with the marines. If you run out of all those heavy weapons you can camp out somewhere and let off shots with your sniper rifle or some other weapon, it should take too many more hits to bring him down if all those heavy weapons haven't already. Relax, don't waste all your hard work by going kamikaze and attacking him, I died many times this way because I got frustrated. The pinger can be tough. Just use common sense and keep at it.
If you have any other tips leave them below in the comments.
******* UPDATE************
I found the fastest way is to collect some C4, hide on the bottom floor right next to where he is about to break through the wall, run up behind him and stick him with the C4 (when you get close enough the reticule turn red and you can stick him). I threw 4 C4's at him, hid in the room at the bottom and hit the button. After that, I used 2 JAW missiles. Then I went and got the swarmer and hit him about 3 times. Now instead of 10+ mins I can beat him in 5mins. I had no idea that you could stick him with C4.
http://www.youtube.com/watch?v=u2FNOIEUCr4
**I'm stuck on a part where you have to escape the prism facility from Hargreaves place. It says escape the PRISM facility get to a safe distance from self destruction, I just can't make it past the gate. If anyone else is having trouble please comment below.
