We could re-write Myth history to say
: that Mjarin was in league with Moagim (Fallen Lord
: perhaps?) which is how he learned those fancy magics
: (the ones above and beyond the Warlock magic) and why
: he wanted Leitrim dead. When he was killed, he used
: magic to keep his head alive.
To be fair, Mjarin was high master of the Warlocks of the Scholomance, and it seems reasonable that he would have naturally known a good deal more powerful magic than that used by regular Warlocks. After all, Moytirra, the founder of the Scholomance, considered herself a magical rival of Mazzarin himself- it stands to reason that the higher echelons of Warlock would be considerably more effective than the "grunt" Warlocks that get sent out to aid allies.