As the title says, add the ability to select any unlocked difficulty to Old One's Army.
Old One's Army seems designed to greatly benefit from the use of sentries. However, newer/returning players who don't already understand this event may not farm the early tiers in order to unlock sentries, thus making their attempts at higher tiers (2, 3), more difficult. More experienced players might see Old One's Army as a roadblock in each of their playthroughs, as they have to farm medals during each tier in order to farm the event efficiently, otherwise acquire all of the other best gear available in that tier which hurts progression. A simple fix would be to add the ability to select the tier of difficulty players would like the event to be, potentially by interacting with the Eternia crystal or the Tavernkeep (maybe in dialog?) -- this can already be done in a tedious way by creating a new world, creating a new arena in that world, and then killing the requisite bosses, but that introduces headaches, especially if the new world lacks a Tavernkeep npc to buy more crystals from. In conclusion, introducing a feature that allows the selection of unlocked difficulties is a solid quality of life mechanic.
Old One's Army seems designed to greatly benefit from the use of sentries. However, newer/returning players who don't already understand this event may not farm the early tiers in order to unlock sentries, thus making their attempts at higher tiers (2, 3), more difficult. More experienced players might see Old One's Army as a roadblock in each of their playthroughs, as they have to farm medals during each tier in order to farm the event efficiently, otherwise acquire all of the other best gear available in that tier which hurts progression. A simple fix would be to add the ability to select the tier of difficulty players would like the event to be, potentially by interacting with the Eternia crystal or the Tavernkeep (maybe in dialog?) -- this can already be done in a tedious way by creating a new world, creating a new arena in that world, and then killing the requisite bosses, but that introduces headaches, especially if the new world lacks a Tavernkeep npc to buy more crystals from. In conclusion, introducing a feature that allows the selection of unlocked difficulties is a solid quality of life mechanic.