I am currently stuck on the final level where cortana tries to open a portal and you get attacked by only crawlers. i finished with that part but now im at the part where you need to go through the portal after picking her up. There are an infinite amount of crawlers and when i try to run through they just kill me fast or they melee me off the cliff. And when i kill them, they just insta spawn more. Are there any tips that can help me with this crap?