for (((Challenge # 038))) it is basically a burn spell unless the controller of the spell it targets either really wants the spell to go through or can't take the damage. Tried to think of how red would counter and "stop that or burn/fry/sear" seemed appropriate

Yeah, that's pretty good. Although it probably wants to do more damage to make it worthwhile and to make countering a sepll a serious possibility: compare Dash Hopes

I dunno; it scales nicely - your huge big game winner? You might need to let that be countered because of its cost. Although it being CMC is a shame for countering fireballs this way...

CMC works with X spells: on the stack, Fireball's cost is plus the mana you paid into , so its CMC is X+1.

Technically, Wizards would probably choose a number, like on Dash Hopes, instead of a number based on a scalable casting cost. That wouldn't be done to make the card simpler... it would be done to avoid the "You shouldn't play big spells because they come with a drawback" effect. According to Wizards, it's more fun if cards like Pyroclasm exist, then, say, Meekstone.

Obviously, Wizards breaks that rule all the time. A recent example is Smite the Monstrous. I just thought that, since we're talking about the subject, the reason why Wizards does the punisher mechanic a certain way should be mentioned.