Eitr Stone

 is used to control the thralls with the carved words, "Okh Eshivar", on it. It also can turn regular water into Eitr.

Richard James Croft found the Eitr Stone in Thailand in 1831, and brought it back to England, and hid beneath his own manor.

Lara Croft found an old file of his father's describing the artefact, and returned to the remains of her manor, to search for it. She found it just in time for Doppelganger's arrival, and used the word to release her from ever taking commands again.