Free/F2P speedup sources ranked. Battle of Constantinople (BoC): 50-220 hours regardless of win/loss (min ~4 chests ~50h if lose <250 score; max ~18 chests ~220h if win with 1,200+). Consuming Return Event (huge, free, repeatable): completing 2.5B of all 4 resources = 640+ days of speedups; 10B all 4 = 3,100+ days; 35B all 4 = 9,500+ days (cumulative). Recommended Keep 25-35 by tier. Gem-consumption returns during the event also grant speedups (8,000,000 gems -> 1,000 days training + 333 days construction; cumulative up to 2,016 days training / 1,104 days construction). Killing bosses (free) -- best per kill: Legendary Cerberus Lv4 248h, Senior Cerberus Lv3 239h, Pan Lv5 205h, Pan Lv4 184h, Pan Lv3 154h; by stamina efficiency Legendary Cerberus 372 min/stamina, Senior Cerberus 358.5, Pan Lv3 308. Verdict: Cerberus and Pan are by far the best, then Ymir, else Griffin/Witch3/Warlord3/Hydra3/Phoenix. Many bosses drop speedups 100% in their chest (Typhon Lv17 27h, Jormungandr Lv16 24h, Ymir5 36h). Random-drop chests: 3 Royal Thieves -> Royal Chest (8h/24h/3-day/7-day speedups); Viking Rescue Chest -> healing speedups. Cerberus1-4 and low Golem/Warlord/Bayard give 0h. For a bot, the strategic move is to hoard resources and time big construction/training pushes to Consuming Return windows -- the single largest free speedup source by orders of magnitude.
Original research source: Evony Guide Wiki