Obsidian Creeper

A new mob that spawns in the Nether. I think it's strange that the creeper is the only one of the four main hostile Overworld mobs that doesn't have a single variant (the others being the zombie, skeleton, and spider), even though it is arguably the most famous hostile mob in the game. So, to fix that, the obsidian creeper now naturally spawns in basalt deltas (rarely) and near ruined portals in the Nether (also rarely, but slightly more commonly than in basalt deltas). Here is some more information about them: 

* Health: 20 (same as normal creeper)

* Speed: (same as normal creeper)

* 10 hidden armor points (blocking about 40% of the damage you do to it). 

* Damage dealt: About 65 (more than a normal creeper, but less than a charged creeper). 

However, the most interesting and unique thing about them is their explosions. Like a normal creeper, they run up to you and then explode if you can't run away or kill them fast enough. However, the explosion does no damage to them, and they do not die from the explosion. They have complete immunity to all explosions except blue wither skulls. After exploding, their eyes fade to black for a few seconds, as they need to recharge. They can still chase you while recharging, but cannot even start to detonate until they are done recharging, which is shown by their eyes returning to their normal color.