Diona provides both shields and healing while dealing Cryo damage off-field, making her valuable in freeze teams or as a survivability layer for fragile carries. Pair her with a main DPS that benefits from Cryo application or elemental reactions like freeze. Build her with HP/Cryo DMG/Healing Bonus on 4-piece Noblesse Oblige or Millelith for team support, or prioritize Cryo DMG if emphasizing her off-field damage potential.