Use with Madurai, and as many casting speed shards as you can. Use with a heat primer of your choice (but don't mod for viral). With a 471% heat and 155% bane primer, every cast will add 7.3x the damage of the last cast to the heat procs. The damage consecutive casts deal would be 1800(8.3^n). Adding on Seeking [Talons], you get slash procs that scale off heat procs, allowing it to scale indefinitely.
The reason why duration is at a minimum is because you want the first heat proc to be that of the primer, not the ability itself. The ability, even at just 0.75s, would refresh the full 6s of the primer