"Oda, if I wait ICly in a vampire den, with invisibility potions or without, to strike at the vampires, if a PC vampire comes on, and is attacked by me there, is it valid, since it is an ambush on vampires, which my character would do, since permanent destruction of such a den is occly not doable."
This is METAGAMING - waiting for some OOC event (like a PLAYER LOGIN) to attack them is absolutely forbidden.
Any similar question can be answered best by reversing the scenario. How would YOU feel if vampire PC lurked where PCs logged in and killed all who entered, including YOUR PC? I think you can see clearly how this would be VERY BAD for our mission here, which is to grow a server that is fun to play.
I caution ALL to read this post twice, very carefully, as I think questions of this nature really can answer themselves. How would you feel if the roles were reversed?
To all PLAYERS - I am hereby cautioning all PLAYERS, this is a place for fun, a place for friends to gather and play a fun game. If your idea of fun is making everyone else miserable, leave now, I do not have time for such foolishness and will not be pleasant at all about such things.
Be well. Game on.