Good luck with that. How many do you know that can make rainbows out of nothing. I think you are underestimating how powerful it is. Let me explain to you how a fight of me VS the Spartans would go.
I start out by making a rainbow. I then fly over head and start to urinate on them. Now they are looking at the rainbows so they do not have up their shields to deflect it. They all go to the nearest lake/river/body of water to wash up and while they have their shields, spears, and swords down to bathe I steal them then use those same weapons to kill them.
No, I would have to find someone who can make leprechauns to get pots of gold at the end of them. Unless I placed the gold there on my own. However, I see no profit in that.
What goddess powers did you get?