If you encounter them, kill them or let them kill you. If you have them chase you, within minutes they will pollute the entire map and make it incredibly difficult to survive forever. Have your admin run a “kill all wild creatures command” if this happens.
When about three spawn, one will turn into a alpha, ( large and orange) which are the ones that drop the venom. WARNING: When they drop the venom, a bag will drop with the venom inside, it won’t go into your or your tames inventory!!! If ten spawn, a reaper will appear. Keep a light pet with you so they don’t overwhelm you. Light pets will burn them, doing major damage. That’s really all you need to know to fight them!