Duskfeather Wings

Loot is rolled once per wave, when its last enemy dies, at that enemy's level. If the roll lands on legendary, every slot with an eligible base is equally likely (Back is 7% as likely as the others), then a base is picked evenly within the slot. Duskfeather Wings is eligible from enemy level 9999. Item level on Normal is 10 × (level − 1) to 10 × level + 9; on Nightmare and Inferno every enemy is level 70 and item level becomes 700 plus the map's level (× 2 on Inferno).