User blog comment:Patrick x hunter/some nen ability's do not work/@comment-27459426-20151224000927/@comment-5780397-20151224025415

I'm not sure about poison gas, it looks more like a Conjuration ability than a Transmutation one. transmuted things have no mass, gas does and is a state of matter, not a form of energy, so it can only be conjured.

As for ice, it is indeed a possible ability for Transmuters, but keep in mind you have to defend yourself if you do not want to be frozen by your own ability: you should do exactly what Genthru does, shield yourself with aura while reducing the ability's power. Or you could emit your cold aura, but you'd need to be very skilled in Emission. However, this is only true is you turn your aura into "cold". If you want to shoot or create ice, you need a lot of moisture. The easiest solution would be to Conjure ice, but some abilities will require that you use Manipulation to move it around.