New skeleton variant concept: The Crusted

Following the concept of skeletons with different arrow effects, I propose The Crusted.

This skeleton-like enemy generates underground, below Y=0, with the exception of the Deep Dark (obviously lol) and Lush Caves, where they don’t spawn. Around 15% of skeletons that generate there will be Crusteds. In underground mountain-like biomes, the Crusted can spawn above Y=0 with a 20% chance of a skeleton being a Crusted, and below Y=0 with a 40% chance.

This skeleton is embedded with stony clumps around its bones that offer extra protection. While it still has 20 HP, normal hits are met with 10–40% damage resistance. Each level of resistance is represented by the number of stone-like formations around the Crusted, 10% being the minimum resistance it can have (even if it lacks visible formations, its bones are reinforced with stone) and 40% being the maximum, with three large stone clumps on its body. The higher the difficulty and local difficulty, the more likely a Crusted is to spawn with more clumps.
Whacking the enemy with a pickaxe, regardless of its material, removes one stone clump from the Crusted. For this to happen, the pickaxe’s attack meter must be at least half charged.

What’s special about the crusted? It shoots Arrows of Infestation, the effect that makes silverfish spawn when the affected individual receives damage. This synergizes perfectly with silverfish, forcing the player to focus on both ranged and look down for close threats.