Recently crafted this legendary and wanted to make up a weak aura to show me only relevant info when I need it.
Tar Trap will show up when Soulforge Embers DoT is not active on any target and when it isn't on cooldown.
Flare will only show up when Tar Trap has been used and when Soulforge Embers is not active on any target.
In addition, Flare will show up when it's off cooldown and when there is 5 or less seconds remaining on Tar Trap, in an attempt to maximize the effectiveness of the weak aura and to try and min-max the DPS, since there's a 5 second window where you can throw another flare into an active tar trap.
On the side there will be a tracker for when Soulforge is active, showing the duration as well as the number of affected targets.
Out of combat, Tar Trap will show with low opacity so you know it's ready to use on your next pull.