Extra data on target debuffs
 

I am using UnitAura() to read target debuffs which is fine and has been for years. Recently I wanted to be able to read the remaining damage, tick damage, on DoTs on targets, but all I can read is the basic stats: spell ID, spell name, count and duration (and some other unrelated stats). This endeavour was prompted by Blizz promising that you will not lose damage if you overlap your Devouring Plagues.

The tooltip on a DoT on a target clearly displays "Suffering 403 Shadow damage every 2.5 sec. 14 seconds remaining" - this is the info I would like to get, is it possible? (someone will say scan the tooltip...)

You could scan the tooltip...



Or use the GetSpellDescription function and parse the text that way.

To answer directly, the server doesn't send that kind of info to the client.
Tooltips are manually written and exist on the client, they may contain embedded formulas, but they aren't always the same calculations run server-side.

Wait, are you saying the various tooltips are fictitious (more or less) ? Surely all the info comes from the server and needs to be adjusted for a thousand modifiers while DoTs are ticking?

If you look on datamining sites like WoWHead, you might find spells with tooltips like "Deals (0.05*AP+8) damage over 12 seconds." The game parses these formulas and replaces them with the appropriate number. These descriptions are stored within the client's data files. The server uses a lot more variables in its own damage calculations and doesn't share that with the client. It's done this way to keep the network traffic per client low.

PS: There have been many patches over the years to fix tooltips that had imprecise and/or outdated formulas.