Simple request. Make defenders purchasable from Purdu if lost (like mage arena capes) at various tiers, bronze through dragon.
OR make defenders farmable at specific tiers.
Who this benefits: 1 benefits everyone, but if we dont want them to be purchasable, option 2 benefits players who are 13, 20 (25), or 30-39 defense, allowing them to stack additional defenders for their accounts.