Strange that no one commented on this. I think this should be uncommon (xspells usually don't go into common anymore), but having a flowstone ability that can boost or kill in pure red is interesting.

Hmm... there are common X spells. X spells that deal damage to players aren't in vogue in common any more, but Death Wind, for example, is a common from Avacyn Restored. Enrage and cards that threaten to deal X damage to players are uncommon... but this one is capped by how tough your creature is. It might be fine. It's very strong for common, admittedly, but I don't know if that makes it 'wrong'.

Ah. My bad. You're right. I don't know where I imagined that X doesn't go to common. Probably from some kind of outdated design article. Haha.

Under NWO, I too thought that X was too confusing for common. It's one of the most questioned mechanics.

Yeah. I don't know what the most common question to Wizard's hotline is lately, but at one time, the number one question was "How does work?". The good news is that there's an intuitive and simple answer for that question. "X = any number".

Wizards did move to have a lot of X cards pulled out of common... even Stream of Life was an uncommon in 2007-2009.

I think they got over it. It's just hard to notice that, since so many X spells are too good for common anyway. Is Slime Molding confusing to new players? Sure. But so isn't protection. If we sat down at a draft, however, and either Blaze or Slime Molding were commons at that draft, I would take those two cards over any other common I saw. I could be drafting blue/white/black, and I'd auto-pick those two cards, with the intent of playing a couple extra mountains or forest in my two color deck. Why? Have you seen what normal seven casting cost commons look like?

­Heat Ray was common in Rise of the Eldrazi. Untamed Might was common in Scars of Mirrodin, and Death Wind was common in Avacyn Restored. It is something they still do, even though they do keep saying it confuses people.

I suppose those three are about as straightforward as an X spell can be, whereas this has the extra confusion of the cost being rather than .

Yeah. I think people who've never played magic would immediately grok more-or-less what Death Wind or Heat Ray does, but I think in a real set, that would be the limit of what's at common, and this would be pushed to a higher rarity because:

• Even if people get X, I bet many, many people will be confused by X1R
• People will be prone to misread +X/-X
• Commons tend to normally do one thing, but this can be either creature kill or occasionally pump
• Red doesn't usually get +X/-X (it does occasionally, such as hybrid riot spikes, but it's often a RB ability).

I think this could be fine as an X spell, or as a +3/-3 instant, but both at once is much too much for common.