Unlike her sisters, Leeuni and Ayuni, Eruni stays immobile during the entire fight. Eruni summons Lesser demons to aid her in combat when her health reaches certain points (one demon in the beginning of the fight, two when at 3/4 life points, three when half and four when at 1/4). Eruni is completely impervious to attacks while there are any demons summoned, meaning the player has to kill the demons off first, causing Eruni's blue magical shield to fade.
Eruni herself mainly attacks with a projectile attack, which is very fast, and hits the player twice per attack, dealing both ranged and magic damage simultaneously. As a result, her attacks cannot be completely negated using prayers. The attacks are capable of causing a lot of damage fast if the player does not use a protection prayer to block out one of the damage types. She does not attack with Melee but instead uses the Lesser demons as her Melee source.