Here are the instructions for the Scythe Witch, one of the phase three Strain from bag 2. The only separate part on this miniature is the right arm - which glues on pretty easily at the shoulder. There is no plug and socket joint, but the parts fit accurately together in the correct position. There is one trickly little injection mark to remove on the tendril - the best way to et this is to hold the part flat against a solid surface (ideally a cutting mat, or piece of thick card), and carefully trim it away with a sharp blade.
Here are the two parts -
Here is the injection mark being removed -
And here's how the parts go together -