OK 2 things 1. Where the hell do you get a scarab gun!!!!!!?

1. The scarab gun is on metropolis, you know the part where you get to the toll booth, before the tunnel? You have to lure a banshee that is shooting you into the tunnel.

As soon as 150 feet into the tunnel where it says Loading...Done, you have to board the banshee, through there you have to drive the banshee all the way through to tunnel.

As soon as you get to the part right before you get out of the tunnel, you have to blow off it's wings and drive through. As soon as you get out of the tunnel go way up and then you will see a big gray bridge to you left it's up there.

2. One skull is in outskirts the very first room you go into the one where you beat down the grunt you know? It's up there before you hit the grunt look up in that room you will see two small platforms jump on one of them it doesn't matter which.

Then look in the direction of where the grunt came from, you have to crough-jump up there. Once your up go to the left in the small alley, theres the blind skull, ask me if you want to know what it does or how to get other skulls.

Ok.You want to get the scarab gun, to get the scarab gun is very difficult, I got the scarab gun on 2-player co-op. You need to be on the level were Sgt. Johnson gives you a tank. What you do is you need to roll over the bridge taken out the Covenant forces along the way, when you reach the end of the bridge you will hear Cortana say "That was quite a welcome party." or something like that and you will have Banshee's, Ghosts and a couple of Wraiths attack you, destroy them all except from at least one Banshee, if you are on 2-player of which I recommend you should do is, get the first player (Or the second it doesn't matter) to go and clear out the tunnel whilst the other player distracts the Banshee.

After the tunnel has been cleared the other player walks (Or runs!) into the tunnel but make sure the Banshee follows, it may take a few shots at you and fly back out (Don't worry though it is perfectly natural) if this happens then run after it and make it follow you again.

Make sure the Banshee follows you to the end of the tunnel were you turn right into the small circular room (Where a Jackel is, dependent on the game difficulty) and thats the first part done. Now here comes the hard part when you turn left to go up towards the exit you will have a checkpoint and the Banshee will vanish, now to avoid this happening you need to get into the Banshee just as the checkpoint is activated.

If done correctly you or player two (Who ever got into the Banshee first) will be able to fly it out of the tunnel now, when you are out of the tunnel fly to your left and you should see two tall sky scrapers, fly up towards the middle of both of them and you should see two bridges, fly onto the nearest one and get out of the banshee, now turn to the left and you should see the scarab gun but, it looks like a plasma rifle.

It has infinite ammo or battery and incredible firepower, but what ever you do don't shoot the ground in front of you or it will kill you and it will be lost. Oh, by the way if it not on the nearest bridge try the farthest bridge. Hope I helped and have fun

Ok. On the first level (that is Cairo Station) when you pass through the armoury after the guy gets shot by a couple of Elites and enter the large room (Where there is a couple of groups of Elites and Grunts.)

Turn around a 180-degrees and you should see a small ledge, jump on it then crouch-jump over the railings, (Whilst avoiding enemy fire.)

Then look up, you should see several more railings going across the platform, now you could do this two ways- One is to walk up a diagonal rail, then jump over the horizontal rails onto a ledge where there is a bin.

Or two, if you have a PLASMA grenade, throw it in front of you and do a grenade jump onto the ledge.

When you get onto the ledge MELEE the bin out of the way, and you should see a skull- pick it up and the screen should flash and/or it should say Thunderstorm or something similar, what this does is it turns all Elites and Grunts into the white armoured versions of themselves.

Yo, get the first skull do not get in the lift (first one) don't get in it untill the man says would it help if I said please then go in it then the second you press x (hold) facing away from the door and you should have it in your hand (it does double damage).