Underground Keycard

2-3 Cathedral: next to the Lepotitsa's corpse, once you kill it behind the altar.

Opens the security door at the bottom of the cathedral's secret exit, towards 2-4 Underground Lab.

That passage has a chest with 4,000 SP (King (Silver)) on the right, before the double doors you both open together. Kill the Lepotitsa before it infects Jenny and Megan for the I Prefer Them Alive achievement; if you save them, a pew by the altar holds a Green Herb and a Red Herb.