Today's GG WoW video discusses Overlays, which have recently jumped into the limelight as it's become clear that they have a tremendous amount of potential power. For a bit of history on this, you can also check out our post here.
The story begins with Warcraftlogs creating a damage meter overlay to accurately show Augmentation Evokers' damage, which was received positively as a nice workaround for in-game damage meters.
This out of game tool updated fairly quickly and led several players to begin experimenting with other tools they could make using the same source, the game's combat log file, which previously was largely thought to update too slowly for any useful mid-fight functionality.
The floodgates have recently opened with reddit posts (eg.
1, 2) beginning to prove the concept could work, with mechanics like Echo of Neltharion's Volcanic Heart being assignable as if it wasn't a Private Aura. Dratnos and Tettles (along with almost everyone they've spoken to in the high-end PvE scene) both hope to avoid a world where these become used, but without any action from Blizzard it's very likely that we will see that happening.
As it stands, these are likely against TOS already, and even the Warcraftlogs damage meter may go against a strict reading of the TOS, but if Blizzard says and does nothing it's likely many players will start to use them anyway. Even if Blizzard says not to use them, Dratnos and Tettles disagree on whether this would be an effective deterrant — Tettles thinks that top teams not using them would be enough to stop them from being widespread and effective, while Dratnos thinks that many would use them due to the fact that, unlike in-game exploits, Blizzard cannot easily detect their use.