Theoryhammer: How would you kill this?

[Denzark]

Charge it with a 50 man fearless conscript squad and watch 1000 points be stuck for 5 turns, whilst the rest of the army takes all the objectives.

[CoffeeGrunt]

uh... yeah... right... against T8... that's gonna take you a while also, they are Imperial (usually), so throwing Emperor-related curses at them isn't going to do much good...
Necrons will really struggle with these, except for Doom Scythes and Night Shrouds, and even those will not kill more than one a turn...

Great rebuttal, well-researched.

Go read the rules for Misfortune, then read the rules for Rending.

[Charon]

Charge it with a 50 man fearless conscript squad and watch 1000 points be stuck for 5 turns, whilst the rest of the army takes all the objectives.

Conscripts won't survive the 5x 5" Barrage bombardement which can also snipe out the priest.

[YorkNecromancer]

Also, what's their Ld like and are they Fearless? Mind War or some of the Dark Eldar wargear options that attack Ld might be an option.

They have Fearless and are essentially immune to psychology on account of being, you know, robots. Their Magos leader isn't, though...

Great rebuttal, well-researched.

Go read the rules for Misfortune, then read the rules for Rending.

Ummmm... I did. Rending gets you round the armour, but it doesn't raise strength, does it? Because at T8, Thanatars are completely immune to lasgun fire; like, it's not 'roll a 6 to wound' it's 'literally you cannot wound this thing on any dice roll'.

They're immune to Bolter fire too. Basically you need a str of 5 MINIMUM to get a roll of 6+ to wound. Plasma only wounds them on a 5+!

[Charistoph]

Ummmm... I did. Rending gets you round the armour, but it doesn't raise strength, does it? Because at T8, Thanatars are completely immune to lasgun fire; like, it's not 'roll a 6 to wound' it's 'literally you cannot wound this thing on any dice roll'.

They're immune to Bolter fire too. Basically you need a str of 5 MINIMUM to get a roll of 6+ to wound. Plasma only wounds them on a 5+!

Rending Auto-Wounds on a To-Wound of 6 at the same time it goes AP: 2.

[YorkNecromancer]

Ah... Then assuming you get in range and survive the cover re-rolling plasma barrage, it's pretty workable. Though I'm not sure you'd kill more than two before being wiped out...

[dimdum]

Right so in my experience the best way to deal with these is close combat. They have a measly 2 attacks, and even with 5 of them isn't that scary to a horde unit or a unit with good invuln. Not only that but their 5++ goes down to a 6++ in combat which is a nice bonus. Don't expect to kill them all, they're tough as nails, but stopping 1000 points of shooting is huge against mechanicum. However if you happen to have force weapons or anything with instant death, ignore that and go wild, mechanicum hate instant death. Do beware though, if the mechanicum player has a magos with cyberthergy (not sure if thats the correct spelling) they can cause them to self destruct resulting in a S8 ap2 large blast to appear where one of the thanatars used to be, so make sure to tie him up as well, if you can. If you have av14, use it and abuse it, thanatars have to get close to hurt you and close isn't where they wanna be.

If you must rely on firepower, against mechanicum you've got to look away from the 'lots and lots of average power shots is best' and look at your quality fire power (unless they run a horde list). This means putting away stuff like wave serpants with scatter lasers and pulling out...well whatever eldar (and other armies) have that is ap3/2, you dont see it too much. Having to change your ways after realising S7 spam doesn't work any more can be frustrating, but replacing the odd wave serpant with a fire prism here and a hornet there has really livened up my games, and if you have a mechanicum player in your midst, well variation in types of firepower is something you're gonna have to embrace.

Characteristic tests are good if you concentrate on initiative and leadership, as these are generally low (is my monolith finally useful? No no it isnt).

[Aventine]

It does have an Inv save - Atomantic Shielding to be precise!

And you can upgrade the unit to have Paragon of Metal, which removes the downside of Programed Behaviour, gaining It Will Not Die and Rampage. Also makes them a Scoring unit (hurr. Score.).....

At least that only works on a single unit of a single model.

In Heresy games I'd say ten-man lascannon support squad is a decent bet, though the Thanatar could wreck the unit in return...

[Wolfshade]

This is it, you don't need to kill it, you can just tar pit it.

[Krargan]

A few ideas from 30k off hand. Mass sniper fire. Legion veteran squads with sniper and infiltrate (ravenguard or alpha legion), Recon squads, infiltrated squad of 10 Iron Warriors terminators (yes, each one has a cyclone missile launcher, infiltrate: See alpha legion troll tactics), A land raider? Or two? Maybe a spartan filled with terminators, like red butchers? or Fire Drakes. They really don't have anything particularly scary to a land raider. Or a thunderhawk gunship.