I finished up my version of the infamous Slamguinius. Captain Slam is must be armed with a Thunder Hammer, a Storm Shield and pretty much necessitates the Eagle's Wing for a Jump Pack, but he definitely needs a JP.
The concept of his use is simple- he is a tactical Nuke. Point him at something your want to die. And it will.
My slam is made from a Blood Angels Chaplain with a Deathwatch Helmet (with the =I= symbol
filled in), Custodes Shield & Spear, Death Watch heavy thunder hammer head and BA Primaris blood drop tokens set into it.