Stand in the doorway of the Farmer's house at Gregorio. Have Gregorio on one side of the door, and your Frost Dragon on the other side, with you standing in between (keeping them from meleeing each other). Your pet will spam spells more often when it's not in melee range. Run Whisper on cooldown.
Have a Bard discord your Frost Dragon, and run the Peacemaking mastery "Resilience" spellsong to boost the pet's MR.