with all these "concalaves" would culexus assassins be a decent pick?

[Sonikgav]

The only reason i can take a Drop Pod is because im running a CAD. Its the only Drop Pod in my list outside of the the Skyhammer Formation so as-per Drop Pod Assault rule it will come in Turn 1, along with the Skyhammer.

If the Deathwing have something similar then sure, run what you like, the only important part to doing it is needing some way of getting a lone, empty Drop Pod from the Fast Attack slot into your list, which in most cases is with a CAD.

[Houghten]

Pure Deathwing don't have a way of taking an empty Drop Pod; only the Venerable Dreadnoughts can take them, and they have to start inside so they can be in Deep Strike Reserve.

[Lord Krungharr]

Culexus is awesome at not only killing psykers, but scaring them away from where you want them to not be. They also provide defensive ability if the enemy tries to maledict you; just move the Culexus within 12" of the cursed unit and it goes away!

Yesterday I played a 2K 3 game tournie with the Execution Force. The Vindicare failed to do much of anything the whole day, his best use is really just to cause a wound with Hellfire (because sniper on a 4+ to wound SUCKS) or to pop light vehicles with the Turbo Pen Str 10 round.

So if I had to pick I'd go Culexus every time, as he's really good in most combats even if there are no psykers around (semi-invisible, and ignoring armor saves, instant death attacks on 6's).

But I do like the Formation...but if used, the 3 non-Vindicare ones need to be used together, almost like a squad. They don't cause enough mayhem on their own, and they die easily enough. But the Eversor and Callidus killed a 30K Arch-Magos and 3 Castellax Automata in I think 3 or 4 rounds of combat and the Eversor continued on to kill a couple Voraxes too.

Oh, and while the drop pod can be handy for the Culexus' placement, on occasion just Infiltrating might be better. Kinda depends on the mission, and where you think your enemy will need to go. Having a transport of some sort to reposition him is pretty handy, as he's slow almost as slow as a guardsmen once the game starts.