You'll start this level off on a bridge where loads of enemies will appear, including a few bikers. The bikers can either be destroyed or avoided, they won't stick around.

Head across the bridge and you'll see a couple of barrels, destroy them to get a bazooka which is extremely effective at taking out large groups of enemies. Head inside the vault and take on the many enemies in this area. Most of them are fairly weak but watch out for the charging fatties.

There are several of these larger foes in this section, after you defeat them all you'll automatically leap onto an elevator, which begins to descend. Enemies will keep dropping down for you to fight...

...and sometimes the elevator will stop, so more bad guys will run onto it. Eventually you'll come to a stop outside a gate with several of the weaker guys dotted around, beat them all and then attack the gate to destroy it and let you continue on.

You'll enter a library with the usual band of enemies including a couple of Bludgers. Barrels will appear at several points in this section, either avoid being hit by them or, more preferably, destroy them to get some items.

After you exit the library you will appear in a similar tunnel section to before, this one has several fatty enemies who charge around and other weaker punks to help them out. After you defeat them you will appear in a computer room where Dr. Fessenden appears on a screen. After taunting you he sends some of his creations to attack you.

"Slisaur" is a mutated version of Slicer, level 4's boss. They still move around with those shadows and still attack with boomerangs; they still have the slicing and boomerang throw attacks, and as usual some other enemies will come and help out too. This is a much more difficult fight than before though as having two of them (three if you are playing a 2 or 3 player game) means you are constantly going to have to move around to avoid being hit. I suggest trying to keep one either side of the screen and making good use of your character's dash attack to beat them.