Its not on a hostile heat spell, its any hostile spell. It just happens to do heat damage.
So, it will do 1065 - 1776 damage over 12 secs (3 ticks, won't get first tick until 4 seconds after it procs)
I'd say the PvP item is better IMO. Its kinda like a Nizara sash.
agressiv
Edit: A lot of it depends whether or not you pay attention to the proc or the description up top. You might just have to test it
