Strange Disease

Strange Disease was a virtual representation of one of Kassandra's genetic memories, relived by Layla Hassan through the portable Animus HR-8.5.

Riddle
''It sounds too good to be true... a spring that heals all? Travel east along the border of Psophis Foothills to find a cave that once housed the Ionides sisterhood of nymphs. I willl be waiting near its entrance on a submerged basin of offerings.''

Outcome
Kassandra found and recovered the treasure.

Reference

 * Assassin's Creed: Odyssey