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Head of gold might not be the best to include because it requires a dedicated Babylonian defense and a lot of Babylonians down at once which does not happen usually. It also makes it harder to incorporate evil characters like Lion or the Serpent or Simon the Magician which are all good evil characters to potentially add without weakening the deck. Great image can basically do the same thing except it only targets heroes and cannot win the battle. I rarely find in a 50 card deck you are able to pull off more than 4 at best. On an unrelated note I like to add Unknown Nation to Babylonian defenses because Nebuchadnezzar. With deck space it might not make the cut, but it can allow you to pull awesome combos.
To be honest, I'd go with Head of Gold over Great Image because Head of Gold is a battle winner, but Great Image is not. Also, even if its only capturing 3-4 humans, how is that bad? Sure it may not capture every Hero, but if your playing Raiders Camp, its an easy chump block.