Then, when he is able to do this and become a force similarly powerful to the Night King (Vladimir Furdik), he can use magic to conjure ancient forces to aid him in his conquest of Westeros, if he doesn’t destroy it first.

The theory, known as the eldritch Apocalypse theory, was first suggested by ASOIAF blogger Poor Quentyn.

The theory suggests Euron will steal a dragon but, on his arrival to Oldtown, he attempts to steal Samwell Tarly’s horn, which is suspected to be the Horn of Joramun which, according to prophecies, could bring down the Wall.

As well as this, given Euron’s wild ways and desire for chaos, he could destroy the wall straight away by blowing the horn on a clear day, if it is indeed this horn which is found in Oldtown.