2017-08-09 12:07PM GMT: I forgot to replace format with string.format. Should be fixed now.
What it does:
Hooks into BigWigs' Sassz'ine module and replaces SayCountdown() with a Voidform-aware clone that will NOT send a message if you have Voidform in order to make sure that your raid mark is clearly visible.
There's a pull request that does the same thing and if it gets merged, this WA will become obsolete: https://github.com/BigWigsMods/BigWigs/pull/342
Why:
If your guild is using a WeakAura that assigns raiders to soak Hydra Shot of a specific mark and you have a Shadow Priest on your roster, you could've noticed that sometimes it is hard to find their mark quickly because of their chat bubble. BigWigs makes you countdown seconds left until Hydra Shot deals damage. It does include a raid mark in the message, but Shadow Priests' messages are sometimes replaced with gibberish due to a "feature" of Voidform.