Lastwall of course got no advance notice of plans to retake Cheliax. The news reached them via one of their wizards Teleporting from the Worldwound saying that someone claiming to be Aroden returned, closed the whole Wound, and then Teleported off to, He said, reclaim His country. 

Iomedae confirms it's Aroden. 

(The wizard, on learning Lastwall does not possess plans to help with that, resigns, and asks if anyone else wants to resign, he can take four in his next Teleport. He gets four of the nearest six people.)

The rest of the news comes in in scattered and somehow increasingly confusing drips over the next few days. Aroden had an army of sorcerers from Rahadoum. No, from another planet. No, both. Aroden used a massive Gate to drop the entire Chelish army in Nirvana. Aroden turned all the soldiers at all the Chelish Worldwound forts to stone. The sorcerers from the other world can mass-manufacture diamonds up to Miracle-grade. Would Lastwall like some to Raise anyone they've themselves lost to Hell.

(Lastwall would.)