I'm trying to come up with a strategy to beat a Chaos Dwarf army that runs 1 (and sometimes 2) Dreadquake Mortars. These things are nasty. Besides the devastation they cause to my Saurus and Skrox units, the attacks can be made to be magical and cause d3 wounds (sorry Slann) and I think the guy I play has a scatter dice that only has Direct Hit sides on it!! The mortar has Toughness 7 and can upgrade to Toughness 8. It can have between 3 and 7 wounds. It comes with 3 dwarfs wearing heavy armor and he upgrades to have a Slave Ogre (+3 wounds, no armor). The FAQ allows the CD player to attribute wounds to either the Ogre or the Dwarfs as he pleases. I would really like to be able to take out the Mortar with Searing Doom and Gehenna's Golden Hounds (targeting his Engineer, and letting the LoS bounce into the Mortar... maybe get lucky with a few and kill the character) So, how does Searing Doom (or more specifically the lore attribute Metalshifting) work against a War Machine that has crew with an armor save? - Does it use the crew's armor save for the "to wound" roll? - Can it not be targeted at all, because the Mortar Model does not have an armor save itself? - Can the Dreadquake Mortar in particular just push the hits off to the armorless Slave Ogre? (or is it considered to always have a 5+ save, and you can't just kill "the dwarf crew" or "the slave ogre"?) If Searing Doom doesn't work, I think my next best bet is to double team Plague of Rust and Transmutation of Lead on the machine and hope my Chameleons and Terradons can get close enough to poison it to death (42 shots per Mortar should do the trick... I might be better off with a 1 in 6 Final Trans....).
Heavens has a nice ant-autiliary spell as well. And the sun standard might help as well. As for the ruling I think there was a general FAQ about warmachines and its crew.
Per the BRB, shooting attacks at a warmachine use the machines toughness but the crews' armor save. Based on this, I think you would use the crew Armor Save for the "to wound" roll for Searing Doom. I don't know about the special rules of the Dreadquake.
Not quite sure why you are using metal for anything, even chaos dwarves, as it really isn't all that great in tandem with lizzie capabilities. There are several spells that would autokill the mortars since they require a characteristic test (e.g. dwellers, pit of shades, etc.). There are also good ones for reducing damage or the ability to fire the mortar (pha's protection, net of amyntok (sneaky since it is a characteristic test which a war machine would autofail), iceshard blizzard).
Well, chamo skinks seem to do pretty well against war machines (especially those with no armour - Empire). If he places them away from his BSB (no no reroll on LD) then any wound made on it will cause a panic test (more than a quarter of the unit's models are removed). Hopefully that can tie him up for a little while