Onslaught OverPower

The Onslaught OverPower promotional Expansion set was released in October 1996 and distributed in packs of Marvel Ultra Onslaught booster packs and inside Marvel Comics comic books in sets of 2.

Marvel Ultra Onslaught
The Character cards were found in Marvel Ultra Onslaught booster packs with a distribution of 1 in 9 packs.

The Mission cards were found in Marvel Ultra Onslaught booster packs with a distribution of 1 in 9 packs.

October 1996 Marvel Comics
The following Marvel Comics comic books contained Onslaught OverPower Special and Event cards. There were 2 cards per comic book.
 * Incredible Hulk #446
 * 2099: World of Tomorrow #2
 * Sensational Spider-Man #9
 * Amazing Spider-Man #416
 * Spectacular Spider-Man #239
 * Cable #36
 * X-Factor #127
 * Excalibur #102
 * X-Man #20
 * X-Force #59