I'd much rather them do something with shadowburn, yeah i know people will disagree with the fact that we only get to use it in execute range, but in my eyes it adds to the exclusivity of the ability. It should feel awesome to hit that button when you can, nothing felt more destro than pulling off 3xsb on a havoc'd add and all three criting, that shit gives me the evil smile.
Maybe this:
Item - Warlock T17 Destruction 4P Bonus When a Burning Ember is filled up, you have a 15% chance for your next Shadowburn to be usable above 20% and to do 50% additional critical hit damage and cause Shadowburn to consume no Burning Embers when cast.
Could feel a little rng tho, so not good when it doesn't proc, but OH BABY when it does consecutively