Stuck in Dark Energy *Major spoilers*

[G-Uni7]

Ok, Alyx has let me down the lift, and I've disposed off the combines, and made my way up to where the portal is. Alyx is in the window behind me telling me Breen's getting away and 2 gunships pop up. I took them out with the energy balls, and have no clue what to do now. Can someone give me so much as a hint. Cheers in advance.

 

[Varsity]

Fire balls into the core. It's the blinding white light at the top of the tower structure.

 

[Iskra]

Yah... then destroy the metalic sheilds... I got stuck here too!

 

[Varsity]

Fire one more into the core itself.

 

[G-Uni7]

Aight, just completed the game, cheers guys ; )