Update from the theorycraft thread. Tormented Souls, Soul Flame, and Wrath of Consumption are all not supposed to require killing blows, merely contribution to the kill. Any situation where do currently do is a bug that will be fixed.
This makes them significantly less useless, especially on bosses with lots of adds. One untalented Seed to mark everything with Corruption means adds packs will each be exploding for Soul Flame damage as they die. Maintaining a 5-stack of WoC won't be unreasonable on a lot of fights. Reap Souls uptime on some fights is going to be approaching 100%.