Imagine a regular Take-Key-to-Gate-Puzzle, but instead of a key it is an hourglass the size of an statue. (Or anything else that could fullfill that role)

BASICS

As soon as you pick it up, a timer starts running and if it ends before you could place it on a special plate in front of the closed gate, then it would poof away and respawn at is original location.

To compensate for difficult scenarios, each time it runs out of time it would respawn with an additional 10 seconds.

The hourglass can be placed down like a key with no penalty on the timer, but will break after 2 hits of enemy attack and attracts aggro as if it was an idle player. If a knight wielding it gets harmed, so will be the hourglass.

If it breaks, it respawns at its original location without the time bonus.

PASSING

The knight wielding the hourglass has a circle projected around him, identical to the blast radius of a bomb (let's say nitronome).
Inside that radius the knights are able to "pass" the hourglass to one another.
(Not necesarily having the throwing animation it could just simply poof to its new wielder, if its too code-heavy.)

To initiate and confirm the pass, the wielder holds the defend button - the other knights inside the radius are prompted with an exclamation mark similar to the quick-chat iconsabove their heads and can confirm the pass by simultaneously pressing attack and defend.

OTHER

Of course it can either be just the timer or just the breaking mechanic as well.

It would be interesting to see an arena with extra loot if you can bring it all the way through. (Yes i'm mad)

Maybe a short countdown continues each time it is on the floor and if the weilder gets hit, then it would drop immediatly, instead of the above.

The timer could be calculated from the tiles between the original location and the gate in a taxicab manner, plus some extra time to account for other puzzles and enemies.