Question on Karr/Nalash pet drops

[Jagwyr]

So I was in the middle of killing Karr when another player flies up and invites me to join his party. Says that he wants credit for the Glorious! achievement, and that he's not interested in loot. I'm not about to trust a random stranger with my already-low odds of getting the pet, but I also feel horribly guilty for not "sharing" credit for the mob. I don't even know how it works -- if I let him join my party AFTER I tagged the mob, would he be eligible to roll on loot? Would I have a chance of losing the pet? This time I didn't risk it, and he proceeded to call me some mean names before flying off... But in the future I'd like to know if it's "safe" to let someone join my party and share credit for the kill in this fashion. Does anybody happen to know for sure? Thank you in advance!!

(The pet didn't drop for me anyway )

[Linaomine]

He would have been able to roll. Don't worry, I'm the same way with any rare's esp because the fun things they can drop have a 5-7 % chance and I'm not losing my super awesome fun item to a random kid that flew up when I was nearly done killing the mob.

[Dalrint]

If they are in your party and do any damage to the boss before it dies, they can roll on any loot that drops, unless you have it set to master looter.

Frankly I wouldn't trust it, I had a guy need on everything from a rare today.

[Jagwyr]

Thank you guys so much for the helpful responses. I'm really glad to have that clarified.. I still feel bad about not being able to share the achievement credit, but at least now I know I'm not being rude for no good reason. Sigh. >.<