A new headquarters, a new enemy and a mysterious machine in the Jim Shooter/Curt Swan tale in Adventure 367 (April 1968).
The Legion are constructing a new headquarters after their battle with the Fatal Five, and the story spends a lot of time showing us the new facilities. They also receive many gifts from around the galaxy.
The Dark Circle are introduced, though who they are and what they want is kept a mystery – for many years, as it turns out. But seeing the Legion busy with the reconstruction, they figure this is a good time to attack the Earth
They assault Tokyo while Karate Kid is there, meeting with his Sensei. At this point, all we learn of the man is that he trained Karate Kid, but he will return in the 70s, and his story expanded.
When the Dark Circle’s forces attack the headquarters, Brainiac 5 wishes silently that Karate Kid was there to help defend them, and then abruptly, Val is there. Brainiac 5 correctly theorizes a mysterious present is the cause, and uses the device, the Miracle Machine, to repel the invasion and complete the new headquarters.
Every Dark Circle operative on Earth is shot off into space, and Curt Swan creates a 60s sci-fi masterpiece in the new hq, which would last until the rebuild in the 80s.
One of the Controllers appears, explaining that the Miracle Machine was a present from them – although at the same time warning them that it can make any thought into reality, and a stray wish could obliterate the universe. Christmas must be a riot with the Controllers.
The Legion seal the Miracle Machine in a cube of inertron, where it stays for many years, though even encased it appears again in the early 70s. The Controllers do not appear again until the late 70s.