Shroomite armor

In order to get this armor, you must get an NPC called Truffle. He will sell the Autohammer, which is used to convert Chlorophyte Bars into Shroomite Bars.

When not moving, you will immediately start entering stealth. Over the course of 1.5 to 2 seconds, you will go through rapid stages of stealth that can be seen visually as partial, to full invisibility. During this time, weapon damage and knockback will be adjusted, and will rapidly climb while stealthing, up to a 45% damage increase at full stealth. This increase affects both weapon and ammo damage.

Set
Set Bonus: Not moving puts you in stealth, increasing ranged ability and reducing chance for enemies to target you.

Tip
Considering the Shroomite Armor only gives bonuses to ranged items, it is advised you should use ranged weapons with this. (UNSURE) Shroomite may be a reference to teemo from League of legends as he places mushrooms and his passive turns him invisible when standing still.