Sculk and Scavenge

Sculk & Scavenge adds two mobs, one boss and one mini-boss encounter. 

All mobs are animated by hand with Geckolib and Blockbench. Their models and textures are also meticulously crafted by myself.

The mini-boss is the Undertaker, a prepared grave scavenger who furtively defends his haul. He is decisive but discreet, acting intelligently to outmaneuver and outgun you. The Undertaker can be found nearby shallow graves that themselves have loot. He himself has loot that he's already obtained, dropping it on death.

The boss is the Sculken Raven, a boss summoned via ritual.
The ritual involves topping a sculk catalyst with a soul lantern, and feeding ten mob deaths to the small two-block structure with an open sky above it. Upon the tenth consumed soul, the soul lantern hatches, and the boss is spawned. 
This boss attacks by pecking, stomping, crashing into the ground, and dive-bombing with sculk projectiles.
This boss has a prestige scaling mechanic - it can get up to four difficulty points depending on how many sculk sensors are nearby - one point per four sensors. Each difficulty adds more rewards to the boss, with a maximum of 4 difficulty, scaling the boss' health, damage, and damage reduction.

This mod requires Geckolib, Architectury, and Cloth Config. The bosses are tuneable via config.