I was playing Brawl using Teval, the Balance Scale as commander, and I wanted to test out Rashmi, Eternities Crafter. I put Rashmi on the battlefield and on my next turn, my first spell was casting my commander. Rashmi triggered, there was a 1 mana spell on top of my library, but I was not able to cast it. See screenshot.

My thought - since I didn't cast it from my hand, it saw the mana value as 0, which 1 would not be less than..