This entire sequence is one of the biggest and most memorable set-pieces in the entire series, as Eva and Snake try to bring down a Volgin-piloted Shagohod. You start by spraying bullets at as many bullet sponge enemies as possible while the Shagohod pursues you around the base, tearing it to pieces, before you get to a runway and the proper fight begins. From here it's your typical "fire as many rockets at the giant mech as humanly possible" boss fight, but once the Shagohod is seemingly defeated, there's an added twist: Volgin jumps out and uses his electricity to re-charge the Shagohod while also attacking from atop the machine himself. As Eva rides around, Snake has to sink more rockets into the Shagohod and fire at Volgin, which is pretty simple stuff as long as you keep moving. This is a great example of a boss fight that's probably a bit too easy considering how late in the game it comes, but it compensates for that with its insane intensity and highly entertaining variety.