Love it. I like how you pinpoint how much this type of effect should cost based off of other cards that have been done before. Flame Slash does 4 damage at sorcery speed for one red. Add an extra point of damage and instant speed, and you get a 1RR spell!
I have found in recent years Wizard is making simpler cards and that in turn has made the game better. I think it is a very worthy study, just like a vanilla creature chart, to make pure, simple cards in each color to understand cost. If this was a green card it would cost 7GGG and possibly still playable. Interesting to think about and I hope to do further study on it. On a side note, I'm thinking of doing a study development of Homelands to keep the intended flavor and power level of the time but making it a much more enjoyable and playable experience. I'm thinking like a Homelands 1.1.
I'd be glad to help you out with that. Let me know if need any insight.