IMPORTANT

Rough Mobs 2 has been released:

https://minecraft.curseforge.com/projects/rough-mobs-2

This project is no longer supported!

Rough Mobs is a small mod which makes some mobs significantly harder.

This mod is pretty well configurable! You can change/disable every feature in your config file.

The mod can also be used server-side only but it is not recommended because some features will be a bit buggy.

Current Features:

Zombies spawn with random enchanted armor and weapons (You can add/remove equipment in the config file).
Zombies have a chance to spawn riding a Zombie Horse.
Zombies have a small chance to spawn as boss zombies which are very strong but they can drop some nice equipment.
Zombies apply the hunger effect to targets (The effect stacks up to level 4).
Zombies have an increased knockback resistance and 30 max HP instead of 20 max HP.
Baby Zombies now burn in sunlight.
Zombies can now break certain (configurable) blocks if they walk through them.
Skeletons (also Wither) spawn with random enchanted armor (You can add/remove equipment in the config file).
Skeletons always spawn with a Bow in their mainhand and a sword/axe in their offhand. If a player is near them Skeletons switch their weapons.
Skeletons have a chance to spawn riding a Skeleton Horse.
Skeletons have a small chance to spawn as boss zombies which are very strong but they can drop some nice equipment.
Skeletons have 30 max HP instead of 20 max HP.
Skeletons shoot a lot faster now. (Decreased bow cooldown from 20 to 0, 1.0.6+)
Skeletons in the Nether always become Wither Skeletons on spawn.
Wither Skeletons spawn now everywhere in the Nether.
Creepers become invisible while they are near a player.
Creepers are a lot faster now.
Creepers explode now a bit faster (1 second fuse time instead of 1.5 seconds, 1.0.6+)
Creepers explosion radius is now a bit bigger (4 instead of 3, 1.0.6+)
Creepers burn in sunlight (Off by default, 1.0.6+)
Creepers explode if they are burning (Off by default, 1.0.6+). Do not combine the last two features except you want a ton of destruction...
Slimes deal a lot more knockback depending on their size.
Slimes have now 50% more HP and can jump further.
Small Slimes can stick on players head to apply nausea and slowness to them.
Endermen drop now at least one enderpearl on death.
Endermen teleport players away who attack them.
Endermen have a chance to apply either blindness or nausea to targets.
Endermen steal and drop held items of targets.

Spiders take no more fall damage.
Spiders apply the slowness effect to targets. The effect stacks up to level 4 while the fifth hit creates a web on the targets position.
Spiders have a chance to spawn with a mob riding it (Mobs can be added/removed in the config file).

Cave Spiders have all new features from normal Spiders.

Witches apply random effects to entities around them.
Witches sometimes throw lingering potions instead of splash potions
Witches spawn 4-7 Bats on death.

Silverfish have a chance to split into two when attacked.

Zombie Pigmen have all new features from normal Zombies.
Zombie Pigmen now also become aggressive if the player touches their hitbox
Zombie Pigmen also have a chance to become aggressive when the player breaks a block around them.

Blazes spawn now everywhere in the Nether.
Blazes have now 30 max HP instead of 20 max HP.
Blazes create explosions on death.
Blazes push the target away and deal damage to him if he attacks them with melee weapons. Always attack them with ranged weapons!
Blazes ignite targets if they touch their hitbox.

Ghasts have now 15 max HP instead of 10 max HP.
Ghasts are now immune to arrows and other projectiles.
Ghasts drop primed TNT when a player is below them.
Fireballs shot by Ghasts create a bigger explosion on impact (Explosion radius increased from 1 to 3, 1.0.6+)

Magma Cubes are now much more common.
Magma Cubes have all new features from normal Slimes.
Magma Cubes regenerate HP while in lava.
Small Magma Cubes drop lava on death. This can be very dangerous if they stick on your head.
Withers have now 600 HP instead of 300 HP.
Withers knock attackers away.
Withers summon Wither Skeletons over time.

Bats can fly on player's head and drain half a heart per second. This feature seems to be a bit buggy on servers.
Skeleton and Zombie Horses now burn in sunlight (1.0.11+ if they have no rider).
Skeleton and Zombie Horses can now break certain (configurable) blocks if they walk through them.
Snowballs melt instantly when thrown in the nether.
Vindicators have now +50% HP and an increased knockback resistance

Evokers have now +100% HP

Endermites teleport players away who attack them.
Endermites apply the wither effect to near players.

Guardians drop water on death.

Also, many mobs have now an increased follow range!

This mod also allows you to add/remove your own attributes to entities on spawn. You can increase: max HP, speed, knockback resistance, attack damage and follow range.

More informations of how this works can be found in the config file and on the wiki page: http://minecraft.gamepedia.com/Attribute

The mod also allows you to create custom entity spawn entrys. More informations can be found in the config file. You can also lower entity spawn rates in the config file.

Mobs no longer attack each other. This was often caused by Skeleton which tried to shoot the player but accidentally hit another mob. Mobs now always search for players around them before they attack. You can add/remove Entities for this feature in the config file.

(1.0.9+) You can now change aggresive mobs to behave aggresive against animals and villagers (Not enabled by default)

If you have any suggestions for new features feel free to post them!

You are allowed to use all of my mods in your modpack! You don't need to credit me.

Mod Reviews:

Review by Mr Super Magic

(A boss Zombie with a beautiful moon background)