Mental Fusion: See Hive Mind for the permanent version (Fusions and Self-Fusions).
The temporary version, called a conflux, is a standard part of the arsenal for a variety of situations – merged fireteams for greater military efficiency and coordination (and, y’know, battlefield omniscience, when done really right), guard webs that share knowledge and raise the alarm simultaneously, research teams thinking in perfect coordination in which the brainpower of the whole is greater than the sum of its parts, and so on and so forth. It takes a lot of attention paid to mental discipline and interpersonal relations to build a team that can do it well, but when it works, it really works.
Pingback: Trope-a-Day: Hive Mind « The Eldraeverse
Pingback: Trope-a-Day: Telepathy | The Eldraeverse