A while a go I read a post about spells not triggering magic epic talents because they're spell power based, and how gun powers can trigger epics because they're weapon power based.
Then I read a post about Witch Hunter starting epic chains with swashbucklers and buccaneers.
Witch Hunter's damage is based off of Spell Power. Test it-- you definitely can now. I did around 1500 damage on an epic hit with it a few minutes ago. And then Mojo Rising activated.
So shouldn't Witch Hunter not trigger chains, or instead should everything else spell-power based start chains?