The T'au are known for their high-tech armor and guns. And one of the highest tech and most powerful is the Pulse Blastcannon. Get a look at this devastating bit of kit in this preview from their upcoming codex for 40k.
From the article:
If the hubbub caused by the latest T’au Empire railgun improvements is anything to go by, the 41st Millennium is going to love all their other big and scary guns. The lumbering Stormsurge carries one such weapon, which is so big and heavy that the Fire Caste were initially hesitant to send it into action. Say hello to the new Strength 16, Damage 12 pulse blastcannon, which packs an awesome punch in the upcoming Codex: T’au Empire.