The Story: "Crisis in the 30th Century!" by Paul Levitz, Martin Pasko, Dick Dillin, and Frank McLaughlin. The JLA and JSA are hanging out for their usual get together when a giant hand materializes in space, grabbing several heroes and then disappearing! I hate when that happens!
Turns out the hand belongs to Mordru, evil wizard of the 30th century! The heroes try and defeat him, but to no avail.
Mordru then explains that he was in pursuit of the magical artifacts bell, jar, and wheel, but accidentally grabbed the heroes instead. Mordru--not the most detail-oriented bad guy in the DCU.
Mordru tells the captive heroes (including some members of the Legion) that he will kill Green Arrow and Black Canary unless they round up the artifacts for him!
The teams of heroes succeed, but they tell Mordru they won't get the last of the items--the red jar--unless he frees their friends. He agrees to this, but when he summons the Demons Three inside the objects--Abnegazar, Rath, and Ghast--they turn the tables on Mordru, zap him with their superior magic, and plan to destroy the magical items which will keep them from being imprisoned ever again!
Roll Call: Superman, Batman, Green Lantern, Green Arrow, Black Canary
Notable Moments: DC still felt compelled to explain the whole Earth-1/Earth-2 thing to readers:
...though that hand deeply disturbs me.
Even though this team-up occurred in the middle of Steve Englehart's run, he did not write the annual JLA/JSA team-up. Turns out Levitz and Pasko really wanted to write it, and, having a bit more "seniority" at DC, got the gig.