After Lord Balor returned to Arcadia to tell of his treatment at the hands of the Mountain King, Lord Gwydion summoned all of the House Founders to council, to discuss their response. At this council it was decided that they would go to war with the Trolls, and so each of the lords assembled their followers into a single great army. This army marched on the Troll stronghold at Undermountain where was fought the Battle of the Riven Mountain.
Of the nine lords, only Lord Leanhaun did not attend the council, for he put his personal quest to slay the Neverway Worm above the concerns of his fellow Sidhe. The members of his House later refused to go into battle without him at their head.
Lord Aelil was a lone voice at the council advising against warring with the Trolls, warning of dire consequences. He refused to help the Sidhe and stated that House Aelil would not be taking part. Lord Aelil himself seemed to help the Trolls in the Battle.