I have 8 very high level bats protecting my Dino pen and during an offline raid on me the bats swarmed the three raiders and managed to kill all three of them. The had journeyman Flak and mastercraft weaponry. So in the near future I will be taming many more of them
Add 10 bats, 5 dimorphodons, 2 centipedes, 3 spiders, 1 rex,1 giga, 2 purlovia, 2 bears,1 theri, 2 griffins, 1 bronto. Get them all to high level with points in damage health mainly, speed for the bats and dimorphodons and I am pretty darn sure no one would get near your base any time soon.