The Island

30' wide, stalagmites (huge, over a dozen, one 15' tall),
steps up (carved from rock), landing area (flat, two
rusting iron manacles bolted to the ground), carved
runes & glyphs.
▶ Read runes: Test Presence DR14. Topics: an
extraterrestrial calendar, blood & sacrifice, the
changing of the seasons, lunar eclipse, the sea, a portal
to the underworld, a nameless god.