Escape Maegor's Holdfast bug?

[anim_master2001]

I am at the point in the Maegor's Holdfast Upper Basement where there is a gas vent. The online guide I found says I must use the R'hllor's vision ability to set the gas on fire and progress. Problem is I have no such ability in my action bar. Also, I cannot use any fire abilities unless in combat. Is this a bug or am I missing something?

[Yasunobu]

Press R and it should work.