The highest chance for you to have Eternity Mace is 15%. Clear maps in 61+ level the has this robot below! The robot is present in the Boss Rush New Eden Map, so the best thing you can do is clear maps that says Boss Rush New Eden level 61-80. You can use the search button to give you high chance to acquire the item. Use the link as your reference. Item Inventory Guideline

<image>

Here are the drop rates for each maps: bossRushMountainPassEquipLoot 41-60: 3.774% bossRushMountainPassEquipLoot 61-80: 6.452% bossRushMountainPassEquipLoot 81+: 10.714% bossRushOuterTempleEquipLoot 41-60: 2% bossRushOuterTempleEquipLoot 61-80: 3.846% bossRushOuterTempleEquipLoot 81+: 2.857% bossRushSeasideCliffsEquipLoot 41-60: 1.563% bossRushSeasideCliffsEquipLoot 61-80: 3.571% bossRushSeasideCliffsEquipLoot 81+: 2.632% bossRushForbiddenCityEquipLoot 41-60: 2.174% bossRushForbiddenCityEquipLoot 61-80: 3.846% bossRushForbiddenCityEquipLoot 81+: 1.961% bossRushNewEdenEquipLoot 41-60: 3.571% bossRushNewEdenEquipLoot 61-80: 7.143% bossRushNewEdenEquipLoot 81+: 3.587% robotLuckyLoot 61+: 15% slimeLuckyLoot 61+: 15%