That's an interesting tweak on the old bolt. Kinda works out oddly though. It's almost white; hurting attacking creatures being the most obvious way it'll go large. Except, well, vigilance is mostly white; which this won't work on - and that's one of red's traditional enemies.

Ah well, I can see it. Though I still pine for the Lightning Bolts of old.

Originally the damage was 5, then I firgured 3 would work best at its cost if I wanted to keep it an instant so that in way could the card be better than lightning bolt.

It's probably right at 3 for current sensibilities. 5 would be bonkers as a 1-cost.