Apollonian Ring

Apollonian Ring is found in Castlevania: Harmony of Despair and is related to the Greek sun-god Apollo. It works much like the Sunstone, but at an increased effect. During the night, it increases defense by 1. During the dau, it is a much increased effect, increasing all of the stats (excluding luck). +6 STR, +5 Def, and +4 for the other stats (CON, INT, MND). It is the counterpart to the Artemisian Ring, which offers the exact same stats, except that it is more powerful in the day.

Found on "The One who is Many" on hard difficulty, but possibly on others as well. In a rare items chest or the boss chest.