How do I kill this massive beast before getting the defibulator pack at the hospital? I have used all my ammo on him and just keep shooting him with the HE Rocket Launcher and he doesn't die! He comes towards me and I keep blasting him! HELP!

When he tears a chunk off the building to throw at you, his heart area shines blue just as he's lifting it over his head; hit that with a rocket while it's shining and he'll stagger back and drop the chunk of building, then come up to you and start pounding his fists around where you're stood. Dodge those, and once he's finished pounding he'll lean over and you'll see the top of his head, also shining blue. Give that another rocket and his life bar goes down. Repeat two more times and he's a goner.

It might be a bit tricksy to get the timing right the first few times, but once you've got the knack for it it's easy enough. Using the zoom on the launcher can help when going for his heart, but it's not strictly necessary. If you run out of rockets there's a vending machine down by where you pick up the launcher that will give you some more as long as the fight lasts.

Oh yeah - and make sure that you've got a valid save from just immediately before you pick up the rocket launcher in case you hit the door-not-opening bug shortly after (hopefully that will be patched soon - it's far more important than anything to do with textures up close).

new player

Well I understand the premise here with this big guy, but I have hit him and had him attack up close and with the building shaking and being forced backwards, etc it's hard to get that skull shot! Also you get only 4 rounds for the rocket launcher at a time (except for the first time you get 12) if you reload right away. I haven't been able to put him down and it's infuriating! LOL!

The timing for the first shot at his heart is the hardest part.
When he comes close and shakes the buliding, the brain shot should be easy.
The difficult part with this is to not take too much damage so instead of permanently evading which interrupts you r aiming, try using a potion that keeps your health up or use bandages if available.
The potions like "adrenaline overdrive" can make difficult sequences in the game a lot easier.

learn his timing. 1 minute and you know the pattern of attack.

Timing is everything here. You must estimate where his heart is and fire just before he throws. If you wait until he throws your shot will always hit his arm and will do no damage. You must fire a second or two before he throws in order to hit his heart. Also, if you move or dodge every time he throws you might never hit his heart because it throws your aim off.
You can take 2 or 3 hits so line up the shot and when he's ready to throw, take the hit he's throwing and fire.
Don't forget, line up your shot and fire just a second or two before he throws.

i timed it so as soon as he holds up the boulder fire the rocket at the open chest part and it should hit it right on time as he throws it or tries to throw it

Or, you can get the rocket launcher before you get there and purchase a [censored]e load of rockets - and
yes, it is available before you go to dead city.

Yup, the Launcher is in Kvasir's sewers, almost right at the exit.

Huh, i have to check this rocket launcher near Kvasir's area, didn't know that ;D And by the way, for me it's bad or very bad, that in the whole game is only one boss and very easy to beat. id should release a story- DLC with new boss, and harder to kill What;s your opinion about it ?

YES.