Blackout Strike + Blackout Combo (icon)
Pretty standard weakaura - tracks the cooldown for Blackout Strike. If you play Blackout Combo the icon will glow when you have the buff. If you want to change it to another effect go to conditions and change it.
Images shows the three possible visuals of the weakaura; not on cooldown - buff inactive, on cooldown - buff active, not on cooldown - buff active.
If anybody have any suggestions or questions hit me up in the comments or on battle.net/discord - info on my profile.