Player Combat
On MCAtlas, PvP is disabled in zones that include the wilderness and in some towns. Towns have the option to toggle PvP combat in their town using /t toggle pvp, If a town has PvP toggled, you'll recieve a warning if you want to go there! You can check if a town has PvP enabled or not by typing /t <townname>. Furthermore, be careful when going into the nether as PvP is enabled in the nether!
PvP rules can be found here. Make sure to read over them carefully!
Here's the warning you will recieve if you try to tp to a town with PvP on
You can report a member who is abusing player combat by following this guide.