This is a continuation and improvement based on the idea of DispelBorder: making it easier for non-mages to be aware of what can we dispell/purge/tranq.
This addon shows a frame containing the dispelable buffs from your target and your focus. In addition, shows a border around dispelable buffs in default buffs frame the same way a mage can see stealable buffs.
Type /df to bring up the configuration screen or use Blizz default place: Interface > Addons > DispelFrames
The addon will also show Ice Block and Divine Shield, even if you cannot dispel them, so you know you canot dispel anything. You can dispel those with Mass Dispel if you are a priest or Shattering Throw if you are a warrior.
Enrage effects are trickier to get right, but for the most part should be fine.