What is the easiest way to beat the final boss on lost kingdoms 2

A really cheap way to defeat the God of Harmony is to place a decoy pillar directly behind it. Now it will want to attack the pillar, but be unable to, so it will just sit there and do nothing. Now feel free to use summons/weapon cards on it at your leisure.
Even cheaper, set up a double-Rheebus (put two Rheebus cards together so that they will heal each other and therefore never run out) behind the God and then put the Decoy Pillar down on the Rheebus' healing area, so that the decoy will also be healed constantly, and you'll have one space left in your hand for summons after summons. Run out of magic stones? You can walk into that healing area whenever you like so it won't matter how many hit points you lose.
Terribly easy win.