Skull's Red Eye

2-1, second crypt: examining the skull makes 2 hooded zombies run off. The one with the eye takes the left route (zipline, traps, spinning blade). Kill it; you can shoot it from inside the tunnel.

Completes the skull by the sealed door, together with the Skull's Gold Tooth.

The blades kill in one hit: when you land next to one, crawl-sprint forward and round the corner. The vent holds 2 acid-spitting zombies and a Whopper: stop in the tunnel after the left-right bend and let the blade deal with the Whopper. This route has more ammo: do it first if you are short.