Do NOT shrink/have a shrink item enabled.
Either use a barbarian campfire inside the mission or make sure they are large races/illusions (no checking for this)
Manually get the mission
Manually zone in
Main assist/Main tank has to be set (no checking for this)
In combat assist make sure no camp is set, manual for tank, chase for others (no checking for this)
Run the script on all the characters
Manually start the event
If you have a ranger/mage manually use them to fire arrows/mag bolts at eggs