THOR

When Thor debuted in Journey Into Mystery Vol. 1 #83 (1962), the enchantment on his hammer carried a timer. If Thor was parted from Mjolnir for more than sixty seconds, the transformation undid itself: the god shrank back into Donald Blake, and the hammer dwindled into Blake's walking cane until he struck it against the ground again. For the first stretch of his career, the thunder god's most persistent opponent was a one-minute countdown.

The writers reached for the rule constantly, and once let it spring the hero instead of trapping him. In Journey Into Mystery Vol. 1 #87 (1962), captors chain Thor in bonds even he cannot break and take the hammer away — and the countdown rescues him, because Blake's slimmer mortal frame slips the shackles, retrieves the cane, and changes back. A year later, in issue #99 (1963), the debuting Mister Hyde forces Thor to drop Mjolnir during a fight aboard a submarine, and Jane Foster hides the hammer, nearly letting the minute expire on purpose.

The timer did not survive the decade. As the Blake identity was used less and less, the sixty-second limit quietly stopped being mentioned, and modern Mjolnir carries no such clause — the worthiness inscription is the only fine print left. But in the Silver Age, every throw of the hammer was a small wager: it always came back, yet the god throwing it was betting his own shape that it would come back in time.