I too am a level 30 conjurer. My tank pet is adept III and I am using the master II defensive stance. I never have trouble with it holding aggro. All my spells however are only adept I or app IV except Shattered Ground the level 25 encounter AOE dot which is adept III.
Against a solo monster, it goes like this.
Send in pet, wait almost 5 seconds.
Start heroic opp, Spiked Rain (3 points in AA), then Burning Agony (3 points in AA) then Frozen by Time (the 5ish second stun) then another Spiked Rain to complete the HO.
I then hit it with Shattered Ground then another Burning Agony then one last Spiked Rain. At this point, most even level solo monsters are at about 5% health and shortly die.