The tooltip for Akarat's Champion - Firestarter states:
Dealing damage burns enemies with the power of Akarat, dealing 460% weapon damage as fire over 3 seconds.
What sources of damage trigger this effect? In particular, I'm asking about the passive equipment procs such as the Fire Chains from Maximus, Fire Walkers, and Pox Faulds. Do those count? What about damage from summoned units (Bowmen from Phalanx) and followers?
Is there a cooldown or do faster ticks/attacks proc the burn more times? Does it stack?