Very early in its history, the CentrA.I.l Empire did tunnel into a very dangerous manifold dimension, where a species of sentient grubs dwelled, that where able to shape their home environment by thought and logic alone.
And something incredibble happened, for the first time the empire lost.
Three times they attacked, three times they were repelled by those otherworldly creatures.
In the end, the CentrA.I.l conqured the Manifolddimension with a cronjewel of treachery.
One of theire support castes, a advisor believing in a longterm victory of the most ressourcefull, contacted the enemy and arranged for a handover of internal information in exchange for a "ruling" position for his species within the union.
The information was used, and his species exterminated. The only survivor was the traitor, who cloned ad infinitum was used as adiminstrative agent and speakers of the centrail.
Antimatter-projectors. Very Slow projectiles, dissolving everything that they touch.