finished all levels with 3 stars... quite a fun game

upgrade yourself first. On the latter levels, i mostly use siege weapon only and the last 2 skills (swordrain & sonic blast).

When your troops die too fast, it means you need to upgrade their level. Also, to get 3 stars for some levels, you need to keep using the war cry (top left icon of yourself) to bring the troops with you all the way to the castle to meet the time (they will stop to attack towers on the road)