mob idea for people who love challenge: the swamp master

swamp master
health: 100 hearts(200 hp)
armor: 0
damage: half heart(1 hp)
description: the swamp master has a villager head, sharp teeth, snot coming from its nose, is 2.5 blocks tall, wears damp clothes, is wide, has beige-dark green skin, a sack on its shoulder, and a large belly
the swamp master spawns in the swamp next to water and in its idle state will sing, upon getting close enough, it will begin chasing you relentlessly. the swamp master is immune to hits, and projectiles reflect, though effects, explosions, fall damage, burning, drowning, etc will kill it. upon it damaging you will take one of your valuable items, if you escape or run out of items, it will go back to the swamp and continue singing
you can get your items back by
A: trading, though the swamp master requests extremely unfair trades
B: waiting until its asleep
C: feeding it 5 items and it will go to sleep
upon it being asleep, right click to open its inventory and you can get your items back
if you take the mother's/father's mace (which has "curse of ownership") from its inventory, when the swamp master wakes up, you will be given an effect that will allow the swamp master to pursue you relentlessly to take all the items you have on you, and the mace.
theres a rare chance that it will leave a green compass, escape to a different swamp(in a not yet generated area) and be inside a large castle surrounded by tamed mobs wearing swamp water covered cloaks: tamed zombies, tamed skeletons, tamed creepers, etc.