One thing? It's unpredictable, so every game is different. Leaders are activated by being drawn from a deck of cards, theres no ugo-igo, but you can also draw cards that cause you to take cards from another two decks. One is a bonus deck which might get you a Re-roll or an extra action with a unit or it might entitle you to take a card from the special event deck. Special events might be a "hidden ditch" or sudden rainstorm that wets bowstrings or a betrayal card leading to the defection of a unit.