1. Siege techniques: Mongolian siege techniques such as returning artillery (counterweighted trebuchets), tunnel warfare, fire attacks, water attacks, ladders, and carts.
2. Psychological game: How the Song army used letters, rumors, fake surrender, and public demonstrations on city walls to undermine the morale of the Mongolian army
3. Double imagery: "Iron Rain" - the rain of projectiles thrown by trebuchets; "Burning City" - the fire of both the offensive and defensive sides and the hope in despair
