A brazen stopwatch built of scrap--it has a single button atop it, each cog that makes it function is fully visible, and it only has six ticks in total. This stopwatch--though it looks common and impractical--is actually an extremely powerful magic item with the capability to rupture space-time; upon pressing the button, you travel exactly six seconds in the past.

This watch has 3 charges. When this item is held in one hand, you can press the button as a free action or as a reaction to an event or another creature's action. When you press the button, expend 1 charge and rewind time by 6 seconds (1 turn/round of combat); all damage you or any other creature received during this time is reversed.  This watch recharges 1d4 - 1 charges at the end of a short or long rest.

Notes: Control, Utility