Broken promise: E Reduce this attacks damage by any amount (minimum 0): Either the next control check your opponent makes this turn gets -X or you draw X cards, X equals have the amount this attacks damage was reduced by.
Now, when the cost says minimum 0, does this mean that the minimum you can reduce it by would be 0 (so you can't reduce it by negative damage, if that even works) or does it mean that the least damge it can be reduced to is 0?