I happened across a good deal on one of each of these bad lads, and I am excited to try em out. What are some techy things to do with them that might not be readily obvious? What are some casters that like them?
It's not as good as running a Dracodile with Mire, but Sturm and Drang can make a reasonably solid list with a Polarity Shielded Meat Thresher. They can TK it, giving it pretty significant threat range, and it synergies well with Dahlia and Skarath by automatically proccing prowl on anything within 3".
I've been experimenting with Helga in thornfall with a thresher. The concealment can make defender's warded brigands hard to remove while valkyries protect the thresher from being shot up too bad, but my meta doesnt seem to take a lot of sprays/anti-concealment. Helga's feat with the thresher can he pretty hilarious.
I still haven't used the sacral vault much so I can't really comment on it.
From playing around with the BEs this is where I see them be best:
1) As Azahul said the Meat Thresher with Sturm and Drang is actually really good. Infantry cant do a whole lot to it when it has Polarity Field on it. Plus Deceleration and extra shield guards help it against shooting. 2) Rask can really crank the Meat Thresher. Gives it a huge threat range, protects it with his feat, has boundless charge and can put fury on it making it POW 19 in melee. Also he will normally have a Swamp Horror to give it Elasticity for a sweet sweet 2" thresh range from its base. 3) Helga has Defenders ward which makes the Meat Thresher DEF 12 and ARM 21, plus her feat is really fun/funny with the steam roller rules 4) Jaga-Jaga with Signs and Portents does quite a bit for both BEs. Her in Blindwater and a bunch of Croak Raiders is probably the best place for a Sacral Vault out of any caster as it will be fully fueled most of the time and Signs and Portents is awesome for it. 5) Maelok having Mortality is actually very very good for the Vault. Means you dont have to worry about tough screwing you out of souls and extra attacks. The only real issue with Maelok is the extreme "Skornergy" with the fact he makes everything in his army undead so no friendly souls for you.
For me personally until some support or casters change even with all the improvements in the BE CID I can't really ever see taking a Sacral Vault. I tried it a tonne after it was updated and in comparison to the Meat Thresher it just never did anything of value. Part of it has to do with more armies are BG focused than infantry focused or if they are infantry focused its Medium Based heavy infantry which the Vault doesnt really do much to.