I am wondering, if someone else has noticed a strange behaviour of Havoc not working correctly, when using Shadowburn with an mouseover-macro.
Since there was a lot Shadowburn sniping in the Horridon heroic fight, I created a mouseovermacro, to better cleave the damage from the low-HP adds on the targets, that need to be killed fast. What got me wondering, if the macro worked correctly was the fact that my Havoc charges were not depleting. With no time to evaluate the logs during the raid and killing the boss finally, I tested it out later on some random mobs in Pandaria and found out that it is possible to reproduce the bug.
The main thing is, that Havoc stops working, when you use mouseover-macros and have the target with Havoc applied as target.
Simply nothing will happen on the target with the debuff, but your Shadowburn will hit the mouseover.
If my english is too confusing, I can create a small video footage,if requested, on how the bug works and therefore you should be aware for that fact, because it has quite a large impact on your DPS.