Seems forge world came out with optional rules for destroyer weapons that tones them down for regular play. This is something that should have been implemented with escalation. Proves yet again forgeworld is the best side of gw.
*Destroyer weapons count as being Strength 10 and have the Instant Death, Sunder and Ignores Cover special rules. In addition, successful invulnerable saves taken against hits from Destroyer Weapons must be re-rolled.
*Each unsaved wound from a destroyer weapon inflicts d3+1 wounds. Each penetrating hit from a destroyer weapon causes d3+1 hull points / rolls once on the appropriate vehicle damage chart.