Necromancer Master spellsFollow

anyone know what mob drops the master verson of Grim Thulian

The MoB is probably going to have to be epic X2 at least, or in a dungeon to have any real chance of dropping your spell. You'll definitely need a group or two who are willing to run through a dungeon and hope to get the named/epic, potentially several dozen times. Any level 34 MoB that is green to you has a chance to drop the spell but we're talking winning the lottery kind of chance with solo or normal group MoB's.

If I were you I would harvest or buy the rare spell component you need and get a sage to make you an Adept 3 version of the spell. The resultant pet will only be slightly weaker than the Master 1 version and cost you a lot less time and/or money. Recent changes to the rate at which spells improve have made Masters less of an upgrade to Adept 3 than they used to be. Also bear in mind the spell will be obsolete when you hit level 48, even the Master version.