Entwinement

"The Oracle did what?" "They just sort of..." "Sort of what?" "They, well, they liquified, sir." "Liquified how?"  "Like they were never solid to begin with, sir. They're currently soaked into the navigators chair and console." "How could something like this happen?" "We don't know sir, but I have a feeling we have another casuality on this ship."  "Who?" "Ensign Seblander, sir." "What happened to him?"  "We don't know, but records say he was the Entwined partner for the Oracle. If this happened to him, then it's likely something happened to Seblander. We just have to find the body." "If it hasn't turned to-" "Aye, sir."

-Transcript from the ghost ship Einsbach

---

Effigies are integral to the working of modern society, but even they, by themselves, are unable to do the tasks that they are required to do. An Oracle cannot plot a course across Dreamspace without the strain burning out every neuron in their constructed brains. A Witch cannot perform its spells without them being equally as dangerous to its own personage as its enemies. An Astrologian cannot read the minds of others without its own thoughts imprinting upon their topic, simply trading information back and forth. Unless an Effigy is entwined.
Once fully constructed, an Effigy and a human can be brought before each other and commence the process known as Entwinement. This is most often done by having the pair sit with their backs against each other and eyes closed or covered. A third party, or one of the pair attempting to Entwine if they're able to compartmentalize enough, will then ask a series of questions that are often philosophical in nature.
This process, depending on how 'in tune' the pairing is, can take several hours or even full days, if the pairing is unable to synchronize their thoughts. Individuals that have a particular distaste for each other can make the process completely insurmountable, leading to common advice being to not let the subjects for Etwinement meet each other beforehand.
The natural psychic openness of Effigys will allow the two minds to build an association with each other, thus forming the basis for the mental connection. Each subject should be able to somewhat feel the thoughts of the other, while not being able to actually read the other's mind. This light form of connection will be the basis the rest of the Entwinement is built upon.
Next, the process will look fairly the same, but instead of simply answering the questions and moving on, the subjects should start answering questions at the same time, and be unsure which of them their answers actually spawned from. When there's little-to-no hesitation in the answers, and the sense of identity between the two is starting to break down, the third stage of the process will commence.
The third stage is similar to the first two and consists of simply asking pre-planned questions to the subjects once again. This time, however, the subjects should be answering as if they were one being, flawlessly switching between their two voices and their individual bases of knowledge. Once sufficient connection has been established, the trance can be broken, and the subjects can carry on like normal. They are now Entwined.
Once Entwined, people will be pointedly aware of each other at all times, with a moderately strong psychic connection between them that is largely impossible to nullify without both being willing to do so. They can feel each other's thoughts, and read them with effort (though the one being read will always know the other has done so). They have a general knowledge of where the other is at at pretty much all times. A directional feeling, if you will.
The most important benefit, however, is the share of mental and psychological strain between the Entwined. This part of the technique is what allows the models of Effigy from earlier to use their more fantastical abilities. Without this facet of Entwinement, the whole process would simply be a bit of a party trick. When Entwinement is complete, the connected individuals are able to 'share the load', so to speak. The mental strain required to access and wrangle Dreamspace would normally be too great for a mortal mind, constructed or othewise, and as such renders such actions a danger to oneself and others until Entwinement is complete.

Inventor(s)

Sofia Faehlmann, Faehlmann Industries

There is no technical limit to the amount of Entwined individuals that can be linked to say, a human mind.
The limiting factor is the ability to get all of those different subjects to get their thoughts to line-up between all of them. The more individuals subject to the process at the same time, the greater amount of mental noise there is to contend with. As you reach the height of what is possible, you will likely require an Astrologians asistance in synching thought patterns.

---

A notable facet of the whole process is that while human minds can be link to things like Colossi without being Entwined (they still require Entwinement to fully access the abilities of a Colossi), they cannot access Dreamspace without outside technology. Effigies, assumedly as a part of their biomechanical physiology, can access Dreamspace and the abilities that it spawns without assistance, but it opens them up to great danger to themselves. Even a momentary touch can cause catastrophic side effects, noted for their many creative things it can do to an Effigies head. 
The short hand term is often the simple descriptor of 'pop', in mimicry of the sound that heads will make during such events. 
Cranial detonation isn't the only thing that can happen, but the effects can be so strange and varied that they don't really bear listing. The bottom line is that the Untwined Effigy in question will perish, either painfully or instantly.