These are basically Iron Golems that have been infected with Sculk...they simply don't have Sculk growing on them...it has made them overpowered aswell..that's why they are boss mobs...Sculk Infected golems are neutral..so you can either hire them as your protectors or for defending your own home..OR...you could defeat them for their rare item drop called 'Sculk Soul'...You can summon a Sculk infected iron Golem by placing iron blocks in a T formation..but the middle iron block has to be replaced with a Sculk block..and pumpkin on top..Sculk infected golems have 300 health..they also regenerate but very slowly..like 10 health in 5 seconds..they hit even harder than regular iron golems..one punch will take away 85% of your health...so better have some strong armour on...but they are a bit easier to defeat than the warden because most of the Sculk infected golem's attacks are melee attacks and not ranged...he will also do a ground pound from time to time in an attempt to smash you....try to dodge all the melee attacks otherwise this guy will smash you into jam...if you defeat this guy..he will drop a 'Sculk Soul'...equipping the Sculk soul in your offhand while punching mobs gives you INSANE STRENGTH AND ATTACK DAMAGE...YOU WILL BE ABLE TO THROW MOBS IN THE AIR AND ONE HIT THEM..It's pretty OP so your troubles of taking this hulking beast down are worth it..if you chose to hire him as a defender..he will easily tear through the mobs as if they are made of paper..his attacks are very OP so ur regular zombies and skellies won't stand a chance at all