The Stone Warrior

BASICS

The Stone Warrior is a mob that will spawn in the Nether, namely Nether Fortresses. To get right into it, it's a mob that has the appearance of a stone statue.

GAMEPLAY

How does it work? Well, it will stand in corners of the halls of a Nether Fortress and stare you down. When you look away from it, it will move slowly towards you. If you are at a difference, the creature will move faster to try and catch you. It uses a stone sword to match it's stone-like design. The stone swords are usually enchanted with decent upgrades, to make them more dangerous in battle. They spawn with 30 health each, and can heal over time. So, you can kill them normally, but it's somewhat difficult. Another way to take them out would be by throwing them into lava. It will instantly kill them.

To make it more diverse, fake phony statues will spawn in corners as well, to try and trick you.

It will drop items like it's sword with a 20% chance. It can also drop 10 cobblestone blocks with 90%. 

NEW IDEAS:

Maybe the Stone Warrior can drop more than just items we already have. What about a new item? How about a weapon? A dagger. What could a dagger do? It has good durability and can help in up to stacks of 16. It can be thrown at long distances, like the Trident. What makes the dagger interesting is that it can be thrown in almost rapid succession if in stacks.