Dead Frontier 2-Outpost Assault Event (DON'T SKIP IT!)

Outpost Assault is an event that rewards you with a powerful two-hour buff upon completion of the twenty-minute-long assault on the player hub, aka the Outpost. This event is great for XP if you are level 15 or lower because all you need to do is tag the mobs, then let the higher-level players kill them. You will both get XP for the kill and besides, everyone is there for the two-hour buff anyways, no one will give two shits about XP leaching.