The breacher was a missile weapon that was in use by the Chiss Ascendancy. Upon impact they exploded into sticky acid globs that ate through the metals of the hulls of spacecraft, making them more vulnerable to laser fire. This made breachers effective even when the missiles were destroyed en route to their targets, because the acid would keep going for a certain range where it could still damage enemy starships.
The use of breachers to weaken an enemy's hull and systems, followed by spectrum lasers targeting the weakened area of the enemy ship, was called a follow-up spread, and formed the basic "one-two punch" of Chiss battle tactics.
Breacher missiles first appeared in Timothy Zahn's 2019 novel Thrawn: Treason, the final installment of the Canon Thrawn trilogy.
Breacher missiles first appeared in Timothy Zahn's 2019 novel Thrawn: Treason, the final installment of the Canon Thrawn trilogy.