Need clarification on Frostfire mage

I must be missing something, When you’re frost spec the hero talent Excess fire says Reaching Maximum stacks of fire mastery causes your next ice lance to apply living bomb, when you’re fire your fire blast instead is the one that will apply living bomb. I don’t know if it’s a bug or not but in frost it procs for both ice lance and fire blast even though fire blast isn’t mentioned at all in the frost version of the frostfire hero tree. Is the double dipping intended or not? Even the fire blast ability lights up like its supposed to be proc.

It is bugged and has been reported multiple times (including by me). Should be fixed and they could also buff a bit Fire Blast too, since it as a cooldown based ability can deal less damage than spammable non-shattered Ice Lance.