Funny. But why the cheaper one have higher attack? I use 1 or 2 dragon + many riders can kill enemies very fast. Rider is cheap and create super fast, only use riders maybe can finish some medium levels.
Another way to defeat the first epic boss is keep about 5000 mana for the last wave. It can let you still alive if you can't kill it in the first round. If the second round still cannot kill him when he pass your main attack tower, throw all your gems to make gem bomb. In this moment you should have many 5+ gems bomb, I don't think that he can still alive.
The hard campaign is very easy..... just put 3 mines in the front can kill most of the enemies. Other medium campaign is harder. 4 slots and 5 slots have big difference.
Mysterious Gold Ninja Armor of Death: Increases hit chance by 100%. critical strike chance by 90% and damage by 0-1000, but sets defence and dodge chance to 0, decreases HP by 80%.
I use shining shuriken, damage 40-1150, hit rate 180%, critical rate 144%.