The aim of this add-on is to make the vanilla game more challenging and increase mob variety, without changing the flow of the game too drastically.

I've balanced it around Hard Difficulty Survival, so it may not function as intended on other settings.
 

Vanilla Mobs

Firstly, I have increased the movement speed, health points and damage of all zombie types (Zombie, Husk) spiders (Regular and Cave Spider), skeletons (Regular Skeletons, Strays and Wither Skeletons), Piglins and Witches.

These mobs have an increased base movement speed (Up to 0.35) across the board.

All health values have been approximately doubled for these mobs.

They also deal on average an extra 5 damage to their regular damage values.

• With the newest update you should be able to survive better starting from scratch but it will be hard!
• I still I recommend you have diamond gear before entering the Nether!

New Mobs

Below are a list of the 19 new mobs I have added to the game:

Regular Mobs

Infected Zombie - HP: 40, Attack Damage: 7 (+ Poison Effect for 3 seconds on hit)

This mob acts like a regular zombie except that it does poison damage with the "poisoned branch" it is holding.

• Place the branch it drops in a crafting table for some extra sticks!

Poison Skeleton - HP: 30, Increased Arrow Damage (+ Poison Effect)

As the name suggests, this mob fires poison arrows. It is based on the Stray, with a new skin.

• It drops poison arrows on death.

Burning Skeleton - HP: 40, Attack Damage: 8 (+ Burning Effect)

These mobs can only be found underground.

• They carry a "Scorched Stone Pick" which inflicts fire damage. You can place the pick in a crafting table to recover some coal.

Redback Spider - HP: 30, Attack Damage: 6 (+ Fatal Poison Effect for 5 seconds on hit )

These mobs are like the smaller cave spiders except that they can be found anywhere and inflict fatal poison. Don't be caught off guard!

Mummy - HP: 40, Attack Damage: 8 (+ Wither Effect for 5 seconds on hit)

These mobs can only be found in the desert and even then they are fairly rare. They inflict a wither attack as they attempt to drain the life out of you.

Volatile Creeper - HP: 30, Explosion Power: 2, Fuse: Instant (+ Causes Fire)

This mob is faster and has more health than a regular creeper. More importantly, it will explode in flames instantly as soon as it is within melee range. To balance things out a little I have reduced the power of the explosion. Its fuse will also trigger as it walks around ready to explode, so you should hear it coming...

Withered Archer - HP:30, Slightly Increased Arrow Damage (+ Wither Effect on hit)

This mob can be found throughout the Nether, in addition to regular skeletons. I've included a wither effect like their stone sword wielding cousins, and their own unique model which features a 3D quiver.

• It drops wither arrows on death.
• They attack any piglins they see (as well as you!)

Soul Skeleton - HP:30, Increased Arrow Damage

These mobs now replace regular skeletons in Soul Sand Valley. They function exactly the same, just with a new model and skin which is more fitting to their setting.

• They attack any piglins they see (as well as you!)

Skeleton Guard - HP:40, Attack 8 (+ Burning Effect on hit)

These mobs can be found anywhere in the Nether, but they are also now summoned by Skeleton Lords. I'm still working on a defensive mechanic for them...

• They carry a "Worn Ancient Sword", 9 of which can be combined to craft a Netherite Scrap.
• They attack any piglins they see (as well as you!)

Infected Pigman - HP: 40, Attack 8 (+ Poison Effect for 3 seconds on hit)

These poor Pigmen have spent too long being exposed to the strange fungi growing in the Nether. It has now started to corrupt their decomposing bodies, causing them to release poison when attacking. Luckily for you though, other Zombie Pigmen will not be provoked when you attack Infected Pigmen.

• They drop the same loot as regular Zombie Pigmen

Improved Texture Lost Skeleton -HP:40, Attack 8 (+ Wither Effect for 10 seconds on hit)

These mobs behave like regular Wither Skeletons, but can be found more widely throughout the Nether. They carry their scabbard on their back. 

• They drop similar loot to Wither Skeletons, except for their iron sword.
• They attack any piglins they see (as well as you!)

NEW Fire Bat - HP:5, Small Fireball Attack

Found in the Nether, these new mobs are mostly quite weak, attacking with a small fireball when you come too close. They do tend to spawn in groups of 2 or 3 so be careful not to underestimate them.

Extra Strong Mobs

The following mobs are stronger than regular mobs and have a life bar which also indicates what type of attacks they inflict.

Wild Ravager - HP: 75, Attack Damage: 12

As the untamed version of their domesticated counterparts, Wild Ravagers may appear more friendly but don't be fooled. They will continually try to charge at you and have extra health.

Zombie Soldier - HP: 60, Attack Damage: 9

This zombie type is much larger than regular zombies, has more health, does more damage and has greater reach than other mobs.

• They drop a "Rusty Iron Sword" which can either be crafted into an iron bar, or polished up to make a "Polished Iron Sword". 

Defective Golem - HP: 75, Attack Damage: 6, Explosion Power: 4 (Fuse: 3 seconds)

Once in a while an Iron Golem will take such a punishing from the endless onslaught of zombies and skeletons that it will start to malfunction and become unstable. This mob's arms no longer function, so instead it will relentlessly charge at you and if it takes enough damage it will explode.

• If you're fast enough (and game enough), as soon as you hear the familiar fizzing fuse sound you can interact with the golem (right click) to recover an xp-bottle to your inventory before the xp is destroyed in the explosion.

Skeleton Lord - HP: 75, Attack Damage: 12 (+ Burning & Slowness Effect)

These mobs can only be found in the Nether. Besides being larger than regular skeletons and having extra health, they inflict a slow effect whilst doing burning damage. They now also summon up to 2 Skeleton Guards every 15 seconds so watch out!

• Skeleton Lords drop a "Scorched Stone Axe" which can either be crafted into a diamond or a "Sharpened Stone Axe" for you to wield yourself.
• They attack any piglins they see (as well as you!)

Pillager Assassin - HP: 65, Attack Damage: 9 (+Slowness Effect), Teleports

These specialist Pillagers work alone, with the soul purpose of hunting you down. Don't let their eye patch fool you, for as a battle-hardened veteran, they can spot you from much further than regular mobs. When within melee range they will randomly teleport whilst attacking you with their dagger. Their skill with a blade allows them to slow you down as they continually change position.

• They drop their dagger, which you can craft into some extra flint, as well as emeralds.
• Update - You can now also use their dagger to attack, as I have increased its damage when equipped.

NEW Alpha Piglin - HP: 75, Attack Damage: 12 (+Knockback Effect), Can aggro any surrounding enemies.

Sometimes a piglin comes along that is simply larger, stronger and downright meaner than the rest. These "Alpha" Piglins have managed to amass considerably more gold than the others, which they love to show off, whilst attempting to gain even more. Notice their golden horned helmet, their golden tipped tusks, their golden earring and of course their large golden battle-axe. On their own they are dangerous enough, but be careful! Alpha Piglins have such a commanding presence that they can rally any nearby enemies to fight for them.

• They drop their battle-axe when killed, which you can use straight away. It deals a great deal of damage, but as a trade-off it will break quite quickly. Think of it as a temporary damage boost.
• They attack any skeletons they see (as well as you!)

Neutral Mobs

Black Bear - HP: 30, Attack Damage: 6

For now this is the only extra neutral/passive mob I've added. It uses the Polar Bear model with a modified texture and spawns in forests.

Recipes

There's also new recipes I've added so that the new weapons the mobs drop can be of some use. You'll notice that these weapons are stackable so as to not take up too much space. You'll also notice that they are very weak (ie 15 or so hits to kill a zombie), which is intentional. However a few can be recrafted to do decent damage.

Poisoned branches will give you a stick when crafted as above.

Scorched Stone Picks will give you 2 pieces of coal.

An Assassin's Dagger will give you two pieces of flint (or you can now wield it yourself)

9 Worn Ancient Swords can be combined to make 1 Netherite Scrap. (Please give me some feedback if this is too unbalanced - wasn't sure about this one!)

Rusty Iron Swords will give you an iron ingot OR ...

... A Polished Iron Sword if you place it with wool and leather as above.

A Scorched Stone Axe will give you a free diamond OR ...

... A Sharpened Stone Axe if you place it with a Blackstone Slab as above.

Special Thanks!

 I'd like to say a big thank-you to u/Chillabyte for the inspiration behind for a few of the new weapon textures. (Mostly the Poisoned Branch and the Scorched Pick). Check them out on Reddit or have a look at their work on Discord  https://discord.gg/geK6WXY  . Fantastic stuff! 😀

Please ...... do not take what I have made and try to re-upload it as your own work, on this site or elsewhere. I'm happy to consider letting you use my creations in any mod-packs etc, but please ask me first and give proper credit. Thanks!

And that's about it! Feel free to leave me feedback and suggestions. I will hopefully add more things to this mod in the weeks to come.