New mobs: Puzzleman and Ghost

I suggest a mob "Puzzleman" that inhabits caves under a specific depth (it would be cool for it to be in any cave, but maybe a dungeon with these mobs would be cool too), is a bit taller than the player and when "killed" it just disassembles to pieces on the ground, only to reassemble and rise again a few seconds later. The damage it does would be 1 heart per second if you're wearing a full diamond armor, but would be very slow. I would say to kill it permanently you need a specific enchantment "Arrangement" in your weapon, but a new material like "Silver" would be cool and able to stun it. Normal material weapons would be able to push it back.

I also suggest a mob "Ghost" that spawns in caves under a specific depth and only when the level of light is under a specific threshold (8 blocks away from a torch, maybe) and with a certain probability. It cannot be hit with normal weapons, making a noise when nearby so it doesn't reach players completely undetected. It would float (and maybe go through certain blocks? not stone though, because it would impact gameplay a lot) and be translucid. Again, maybe it could be stunned by a silver weapon, pushed back with any weapon of any material and permanently killed with the enchantment "Afterlight" or made disappear by placing a torch.

I think combat and enemies in Minecraft have a lot of room for growth and it would make travelling and exploring caves a lot more amazing than it already is.