This guide is for barbarian to gain exp and level up by fighting with zombies. To get more exp you need to kill zombies as many as possible, cause it's important to make mother zombie spit out more zombies in the battles.
Leading up to find zombie hole, you need to make some preparation. First, reduce dps. High dps may kill zombies soon and miss the goal, while too low will lead to your death. Then improve viability. Choose equipment with the option reduce damage from melee attacks and each hit adds life to make up the defects of not high dps.
The next is to find suitable equipment. Just change weapon, gloves, necklace and rings to the ones with the options mentioned before. The rest can be set as normal. Here are some recommend items: Stormshield, Skull Grasp, Immortal King's Irons.
This legendary shield value is the wonderful block amount. As to the weapon, you can choose a nice dagger for it.
Skull Grasp has the option Increases Critical Hit Chance of Whirlwind, which helps to strengthen the skill.
Immortal King's Irons, reduce damage from melee attacks.
Let's see the skill build.
The main skill in this build is Seismic Slam. The ability “Slam the ground and cause a wave of destruction that deals 240% weapon damage and Knockback to targets in a 45 yard arc” is strong enough to make all the zombies fall into disorder. With the rune Strength from Earth, it can work infinitely in the fighting. Now it's time for you to practice.