Pointed Discussion

I can't really see a Firebreathing variant being at all green.

It's called "Ursapine."

If you got it out, you have six mana available. So it's a common that can be a 9/6 on its first attack.
I stuck one in a red/green defender ramp pauper deck with Overgrown Battlement and Vent Sentinel. Makes a nice mana sink if I don't draw into any -burn spells.

If you fear this card, then you're a fool.

I could compare this to Terra Stomper at the same CMC, but comparing older cards to newer ones is unfair, even if there was only one set between them.

No, any card cost green creature that requires a turn to be slightly better (one toughness) then Craw Wurm is a massive failure. Sure, it has the ability to pump further, but only in multiples of 3, meaning you can't pump it further than 9/6 until you hit nine land, and it will just get chump blocked all day. Horrible.

Limited filler, move along!

I prefer Chrome Birch