Eris, for as quirky and energetic as she seems in Hades 2, is actually a very fearsome combatant. Her boss battle fought up on the surface is pretty widely regarded as being very difficult, second to only Chronos, at least in the current state of the game's Early Access. There are a multitude of reasons as to why Eris' encounter is so hard, but one of the primary ones has to do with her range. She's using the Exagryph, otherwise known as the Adamant Rail, a weapon anyone who played the first Hades game is going to be more than familiar with already.