Originally Posted by
dday3six
For reference both Physick and Eye for an Eye work, and you can cross Stoneskin as well.
However, the main idea is so the player does not carelessly use the pet. Making it invincible would make it the "best" tank in the game assuming aggro is held, beyond the free, no downtime damage/healing. Tools to keep the pet alive are wasteful when proper placement and movement can do the same. Besides which unless they were free, simply re-summoning would be more cost effective in the long-run anyhow.