In the Merfolk game, I wasn't able to 'clasm against a field of 2/2s because he had an untapped AEther Vial ready to drop a lord. In the CoCo Elves game, the same thing happened when he responded to my 'clasm with a CoCo, dropping a pair of Elvish Archdruids to save the day.
I stayed in the tourney to keep testing, losing round 3 to Affinity because my 'clasm couldn't deal with his man-lands.
![>:-| :argh:](./images/smilies/argh.gif)
On the plus side, I think Burn is dropping off, freeing up the Kor Firewalker spot in favor of something else (thinking Magma Jet).