Chroniton torpedo

From Memory Alpha, the free Star Trek reference

A chroniton torpedo is a projectile weapon based on temporal science. They were used by the Krenim Imperium in various timelines, and were able to pass unhindered through the shields of enemy ships due to their existing in a state of temporal flux. Some Krenim chroniton torpedoes operated on a temporal variance of 1.47 microseconds. (VOY: "Before and After", "Year of Hell")

In an alternate 2374, the USS Voyager suffered heavy damage from chroniton torpedoes as it passed through Krenim space. Eventually, Seven of Nine and Tuvok developed temporal shields which were effective in protecting Voyager. (VOY: "Year of Hell")

In another alternate timeline, the crew of the Voyager were able to disable the Krenim torpedo launchers before they fired, by recalibrating the targeting scanners to a parametric frequency. (VOY: "Before and After")