This whole thing was actually a hoax from the very beginning.
"Gold Rush", "Spiritual Leash", and the quest "Wakfu Flood: Excarnam to Inglorium" do not exist and have never existed on the beta server.
The beta server's main text file (the file that holds literally all of the text that can appear in the game, located in your Ankama\WakfuBeta\game\contents\i18n\ folder) makes no mention of any of these things in French or in English.
This is most likely all that happened:
A duel was started with the Enu and Osa.
The Enu spent the entire battle filling the map with gold mines by digging them up with a drheller and using Mine Mover. While the Enu filled the map with gold mines, the Osa collected +control from the speed/initiative bonuses. The control gained from speed bonuses does last for the entire battle.
By the time the map was entirely filled with gold mines, the Osa probably had enough, or nearly enough, control to summon everything in the gobgob.
These two classes were the perfect choices since they can both do something that looks interesting after spending a really long time in a battle. (A pretty map full of gold mines and having 5 high level summons out at once.)
While being a little bit vague about it, Tommy did basically admit it was a hoax here.
This was all only, what I assume to be, a late April Fool's prank and nothing more. (And I have to admit, it was very well-played on Tommy's part and everyone else in the thread who played along with the prank. )
This post has been edited by [MOD]Gataki - January 22, 2017, 13:08:00.