feather/ash conversion is 1:X where X is the number of pieces of armor equipped when the loot roll takes place. X must be > 0 during queue time.

Optimal strategy:

1. Equip the class armor piece and queue
2. Complete the event and kill the boss
3. Switch to a loadout with 5 armor pieces between the boss dying, and the loot rolling

You will get the optimal 1:5 conversion with this method. Up to 20 feathers per run can be consumed based on the number of balls successfully thrown at the bonfire