Blizzard has announced that the Arcane Influence achievement will be available until tomorrow, 3 p.m. Pacific time. After that, the Valdrakken forge will be permanently powered. Note that this does not affect other parts of the Secrets of Azeroth event.
You can see the countdown below to the when the event will be last available.
Okay hear me out–It looks like it’s actually, really, definitely going to be available until 3:00 p.m.