The problem is getting your pet to actually tank and not train enemies right back to you every time you move while its fighting. I find it quite irritating that the developers could not find the time to upgrade pet control while in the process of doing so for henchmen and heroes.
Just for fun here is the build I came up with. Although it might be old news and I just never heard of it, I don't check the fourms as often as I should.
R/Mo
12 protection prayers
9 + 3 + 1 Beast Mastery
66 Left over attribute points
Life Barrier [Elite]
Life Bond
Call of protection
Charm animal
Comfort animal
Cast Balthazar's Spirit on yourself and you gain energy whenever your pet takes damage
This combo will make your pet invincible to anything under 60 damage and it will take a whopping 11 damage from a 100 damage attack
