Soul Ignition doesn't initiate combat. Not sure if this is intentional but I doubt it as I've been able to kill every enemy that doesn't have combat initiated by convo without entering combat. They (the bad guys or good guys) just stand there as the DoT ticks away until they die

 

I have seen this as well. I doubt this is working as intended, as long as you have Focus in your pool, you can kill just about anything with Soul Ignition.