Dragon and Wards
This is less of a bug and more of an exploit, but wards (pink, yellow, green) should not be able to be placed of where Dragon sleeps similar to how Baron works with wards, this is kind of a really cheap tactic to make wards invincible since supports and junglers do not want to kill a ward and take a bunch of damage from dragon since you have to leash the Dragon, pull it out of the pit, attack the ward, and lose all your HP in the process.