We all know it's a pain to wait while TB chills out, or gets enranged. What if Fire Nova/Frost Nova each helped him control the change just by learning these skills?
Fire Nova: Each point decreases time to shift fire->Ice by 30%
Frost Nova: Each point decreases time to shift to Ice->Fire by 30%
This is in addition to the activated ability of course.
The idea is that it would give people trying to pull a 'hybrid' build some additional help. Quick switching back and forth, even if in only one direction, would make for interesting game build options.