Ever wondered why your pet would disappear at nearly full health?
I've been in this situation several times, in the middle of a fight suddenly - *poof* - the fully buffed pet was gone. At first I thougt that it was a bug or that new mobs (post PoR) got a new ability to dismiss pets, but yesterday a friend of mine told me the real reason:
IT'S THE SHROOM !!!
Do you have the Freemind Spore Earring (Halloween quest) or the Lunar Fungus (8th anniversary scavenger hunt)? When you have your pet up, you cannot get the shroom as second pet, but you still get the corresponding buff from these items.
The main disadvantage is that if the buff fades (being dispelled by a DoT or elapsing), your pet goes with it.
Pet classes should think twice before using the shrooms...