Core mechanic: in Evony monster/boss battles, a single battle will never wound more than 10% of the troops sent (verified). Exploit: send 10x the number of troops you want wounded and deliberately lose — e.g., to get exactly 200 wounded troops, attack a monster with 2,000 troops and lose on purpose. Use non-ground troop types for a reliable 10% cap (ground-only troops reportedly can wound at less than 10%). If the Monarch Talent 'Mortality' (Lv6) is selected, the wound cap drops to 5%, so you then need 20x the troops instead of 10x. Primary use case: events that reward you for healing a set number of troops — e.g. trade-goods events (Eagle of Freedom, Strong Drink, Shining Treasure, Silk Road, Fragrance, Tea Culture) where healing 30,000 troops yields 300 exchange items, and 200 of those exchange for 500 medals — plus the daily 'heal troops' activity score, and pre-staging wounded troops before events like the Monarch Competition 'Power Increase' stage.
Original research source: Evony Guide Wiki