The Neptunium Golem is a post-Helvius boss. Progression Map Page: Post-Helvius
The Neptunium Golem can be summoned at a Summoning Station using a Neptunium Crystal as the ignition.
The Neptunium Golem has 1024 health, deals 20 attack damage, and has 4 attacks. The Golem will not take damage from long range attacks (5 or more blocks away). The Golem will despawn once all players are dead, so it must be killed without dying in singleplayer.
The first golem attack features a ground-pound area of effect that can be dodged with a timed jump. Wearing full neptunium armor and getting hit by this attack will leave you at half a heart. This attack occurs every 50 seconds.
The second attack will occur when you have left the radius of the golem (15 blocks) for 5 seconds in total. The golem will simply teleport to your exact position.
The third attack occurs about every 67 seconds and the golem will be slowed down substantially for 1.5 seconds and will dash at you extremely fast after.
The fourth and final attack features another massive area of effect. However, it cannot be dodged by jumping. The golem will move a lot slower and you will receive a warning sound that signifies you have 4 seconds to get 15 blocks away from the boss. Once you are out of this radius, you are safe. The damage wearing full neptunium armor will also leave you at half a heart. This attack occurs every 25 seconds in total when the player is out of the 9-block radius.
The Neptunium Golem will instantly kill almost any hostile creature that comes within a 5-block radius of it as a method of self-defense and to prevent boss cheesing.
The Neptunium Golem drops one Neptunium Ingot, a crafting ingredient to the Neptunium Pickaxe, crafted at a Haven Altar.