The Reliquary Altar

At the far end of the crypt hall waits a reliquary that grants a boon once a night. Claim it and a stone slab grinds over the way out: the Vigil begins, the sarcophagi open, and the Guardian rises last.

Wrangle the Guardian and the slab lifts again. It's the crypt's little gate home, too — the risers you calm drift here.