A good idea for those issues that happened in the Vault with the tank wall pulling.. while the dungeon is starting.. type out a message for the tank..

Something like "Hey this is my first time here, can we do smaller pools so I can learn the dungeon?" Or something simular.. just let em know your new and would like smaller pools..

A good tank will understand an accommodate you on it.. a bad one well.. you just can't do anything about those kinda tanks..