You have to complete Act l to unlock Act ll. Simply select it from the main menu and play through the quest. This act took me about 3 hours (I failed a couple times so can be done sooner). Some notes on this Act to make it easier:
- Don't skip too many turns at the beginning. You start with a negative blood income and need to capture some villages.
- Avoid large side battles at the beginning until you have a stronger army (around 100 will be OK). I failed many times because I tried to claim a ritual stone battle.
- Claim every province you can for easy XP. Put your legacy points to blood income and then attack/defense.