for anybody that needs to know how to beat the flying merchant here is how. You go into the room with the floor switch which drops spikes. Wait till the merchant is pretty close to you but then step on the switch and duck. The spikes should impale the merchant and kill him. Also as a side note when he is dead wait for the spikes to go up before you stop ducking.
When I saw this I thought it was a Crush the Castle clone. However it was a very fun new way for the castle destroying series, complete with some epic music.