The soul tank is a fun build using the cursed axe, wither armor, and harp crossbow. Wither armor increases survivability and gives you increased soul gathering, the Cursed axe is just a very powerful weapon, with radiance increasing survivability as well. The harp crossbow is just there because its a very good bow. As for artifacts, we have the torment quiver, and two deathcap mushrooms. We can get increased value out of the torment quiver because of how many arrows the harp crossbow fires, and the deathcap mushrooms provide extra attack speed, and because of the cooldown enchantment on the wither armor, you can keep this up indefinitely.