How much xp is gained if the pet's out when you kill a mob on your char?
the exp you get = the exp your pet gets
also, if your in a party a pet will NOT reduce the total amount of xp gained. no matter what the sharing rule is
example:
you go do ciar alone, while there are 3 other players in your party (but not in the dungeon)
-you kill a goblin -> goblin gives exp
-exp gets divided by 4 (because theres 4 people in the party, including yourself)
-only you get the exp, since the others are "too far away" to recieve the exp. it stays divided tho
another example:
you do ciar with a pet summoned, there are 3 other players in your party (not in the dungeon). 2 of these others also have pets out
-you kill a goblin -> goblin gives exp
-exp gets divided by 4 (you + the 3 other players, pets do not count for division)
-you get the exp (even tho it stays divided)
-your pet gets the same amount of exp you got
-other players don't get exp, since they are too far away
-their pets don't get exp either, since their masters don't get any
ps: you can summon a pet and make it sit at the entrance of the dungeon, since it gets the same amount of exp you get. as long as your character gets the exp your summoned pet gets it as well, therefore only you need to be in "range" of the exp
pps: if you didnt know yet, exp has a range limit for players (being 3-4 rooms big). if your player isn't in that range limit you won't get the exp. this was implemented to prevent power-leveling someone who's afk