From my experience the working strategy against Lich is being more offensive :
- block/heal on weak rolls
- Attack if you have more dice value then Lich can block.
-Wait for good roll like 6, 5, 6, 4, 3.
- Use 4 and 3 to trigger "7" skill and get 2x boost
- Use other dice for attack. (You should deal 17 x2 = 34 damage this way.)
- after 2-3 attacks like that you should be done even if Lich heals or blocks. (He has 50 HP)
This way the fight usually take like 3-5 turns to finish. Being defensive gives Lich a chance to heal and fight will go forever.
There is still more in the game (2 more enemies on swamps and final fight with Big Bad). I encourage you to give it a second chance ;)