Ultimate Mob Farms

Ultimate Mob Farms adds all the things you may need for mob farming.

This mod has integration with Reliable Recipe Viewer, and I really recommend using it.
All items also have descriptions visible by holding shift while hovering over the item when using the Item Descriptions mod.

Below is a quick summary of things the mod adds. For more details, see the documentation.

Features

Soul Essence

Soul essence is obtained by killing any mob while they're standing above either soul soil or soul sand.

Spawner Shard

Spawner shards are dropped when a monster spawner is broken, or can be crafted using soul essence and iron or copper bars.

Spawner changes

Spawner can now be crafted using spawner shards and an echo shard, and can be picked up using silk touch.

To make mob farming even more fun, you could be interested in projects like Upgradeable Spawners, Apothic Spawners or anything else dealing with making spawners upgradeable.

Soul Gems

Coating a diamond with soul essence gives it the ability to trap souls, crafting diamonds and soul essence together results in an empty soul gem.

The empty soul gem can then be filled by holding it when killing a mob, trapping its soul inside the gem.
Once enough souls are trapped and the gem is filled, it can be used like a spawn egg to change the mob a spawner spawns, or be used in the compact mob farm.

Compact Mob Farm

The compact mob farm does what it says on the tin, it allows you to farm mobs in a single block space.
Just place it down, insert a soul gem, add a hopper and watch it fill with items.

Different mobs require different tier upgrades that enhance the containment capabilities of the compact mob farm.

The compact mob farm has an internal, inaccessible inventory that can hold an infinite amount of stacks of different items, each limited to 64. Drops will get voided if it fills up.
A hopper or some other method of extraction must be used to retrieve the items from inside this inventory.

Item Collector

The item collector will collect items in a 3x3x3 box and send them straight into a connected inventory, the range can be increased with upgrades.
The outline of the collection range can be seen by shift right-clicking on the block with an empty hand.

XP Collector

The XP collector will collect xp orbs in a 3x3x3 box and convert them into bottles of experience and put them into a connected inventory, the range can be increased with upgrades.
The outline of the collection range can be seen by shift right-clicking on the block with an empty hand.

The item that xp turns into is configurable in the config.

Soul Spikes

Soul spikes will damage any mobs that touch it and multiply fall damage.
Damage from soul spikes is counted as player damage, so it drops XP and player-only drops.

Soul Fan

The soul fan will push entities that are in front of it. The range can be increased with upgrades.