Turn One: The Guard went first, Even with most of the Vanquishers only needing a 3+ to hit, it still took four of them to drop the Void Shields. The remaining six did 4 hull points of damage, all from the Vanquisher battle cannons. The Baneblade did single point of damage with its main gun and none from the lascannons. The pair of Shadowswords inflicted seven points of damage with their mighty Volcano Cannons. 12 points of damage total, almost half.
Then Tempestus Rex shot back. The Shadowswords were clearly the biggest threat and each got erased by a triple turbo laser battery. The Baneblade and a Vanquisher were taken out by a single Volcano blast, and the formation HQ tank plus a two of his friends by the second Volcano Cannon shot.
The six remaining Vanquishers (now hitting on 4+ due to the loss of the HQ) Took down the Voids and did 3 more HP. Then they died.
No big surprise that the Warlord Titan is a nigh unstoppable machine of destruction, and doesn't really belong in a 40K scaled game. But it is so much damn fun!
The Emperor Protects
But Size Does Matter