Leylines are weaves of magical energy that flow throughout the universe. Each of these weaves have different effects and usages.
The leyline theory in Magaambya, states that these leylines can be harnessed to connect certain points of the oval planet to another to create portals. 
The part where this becomes a conspiracy theory, though, is where this links into a few questionable actions Jetembe has taken, amongst them "why is the university here at all?" The university grounds used to be a fucking swamp, middle of nowhere, with nothing of importance to speak of and a lot of other potential locations that would have been benefitial for the university to be made. the theory notes that the university has A PORTAL somewhere within it that connects to an area Jetembe wanted to hide/keep control over. The theory goes on to note that there are additional portals in the elven sanctuaries(hence why nobody is let in) and screaming jungle(a corrupted portal in particular, hence why people get nightmares there. 

[on the runes]
Certain shapes have power, and rune magic, for example, is a more primal strain of magic that takes certain shapes and uses them to create effects. And runes have been found all over Magaambya, lending power to the conspiracy theory.
There are several artifacts hidden and contained in the university that are being targeted by the insect attacks. We've also found a secret door in the dormitory stairs. 

[Yun's extra conspiracy theory]
The old man jetembe destroyed a particular area, nuked it hard enough to make it magically radioactive. it might be that whatever our portal connects to from Magaambya is hidden within this area. 

=== Screaming Jungle ===