Nova flame is supposed to reduce perfect block chance to 0 as well as block proficiency to 0. This sometimes does not work.
Here is a screenshot of perfect block while Nova Flame is active

Here is a screenshot of block proficiency not being reduced while Nova Flame is active (blocked hit did only 84 damage)

In the first fight I entered Nova form after using the SP3. In the second fight I was in Nova form for the entire fight from the pre-fight ability.