What can I do to avoid it?
1. Do not train in a map that has visibly more mobs than another map;
2. Do not "AFK" while in a map (namely Lionking Castle or Stronghold), the leader of the party can (and probably will) invite a hacker into the party to go faster;
3. Do not knowingly train in a map that has a hacker in it;
4. If you see a hacker in a map, "vac hacking", do not kill steal their mobs;
5. If you see a hacker in a map, "vac hacking", do not pick up their drops;
6. Do not buy hacked items. PLEASE inform yourselves before buying an item that you might think is all right to buy. For example, any Cash Shop items, always be careful when buying those.