Mob Grinding Utils — Guide

Fans

Fans move mobs without water channels or pistons.

A fan blows a steady stream of air in the direction it faces, shoving any mob in front of it.
Chain fans along a floor to herd spawned mobs from the spawner toward the kill zone.
Fans can also push mobs off ledges or hold them in place against a wall, giving you full control of mob flow with no redstone timing.

Point the fans so the airflow funnels every spawned mob into a single corner or channel where your killing block waits.

The Absorption Hopper is the collection hub of the farm.

It vacuums up every item drop in a wide area around itself - no need to line the floor with hoppers.
Connect it to a chest or storage system and it funnels all the loot in automatically.
It also pulls in the experience orbs from the killed mobs and pipes that XP into an attached XP Tank, so nothing is wasted.
Tank and filter upgrades let it hold more and sort what it keeps.

Place it under or beside the kill zone so its collection radius covers where mobs die.

These two blocks store and bank the experience your farm produces.

Stores liquid experience collected by the Absorption Hopper.
Acts as the fuel reservoir the Mob Spawner draws from, and as a buffer you can draw XP back out of.
Tank upgrades raise its capacity for big farms.

Converts stored liquid experience into Solidified Experience - a solid block/item you can pick up and carry.
Lets you bank XP for later and cash it in when you need to enchant or repair, instead of losing it on death.

Together they make experience a storable, portable resource rather than something that vanishes if you walk away.

The lassos let you capture and move mobs.

Used on passive mobs (animals and other friendly creatures).
Right-click a mob to scoop it into the lasso; right-click the ground to release it unharmed.
Great for relocating breeding animals or stocking a farm with a starter mob.

The hostile-mob counterpart - captures monsters that the Golden Lasso cannot.
Lets you safely carry a dangerous mob from where you found it to your spawner or holding pen.

Lassos make it easy to gather the exact mobs you want before sampling them with a Mob Swab.

Choose the mob to match the drop - swab a creeper for gunpowder, a skeleton for bones and arrows, a spider for string.
Funnel with fans into a single kill block rather than many - it keeps the farm compact and reliable.
Always route XP into an XP Tank so the spawner stays fueled and experience is never wasted.
Use spikes for XP - they drop the mob's experience, unlike a plain drop kill.
Solidify spare experience before risky trips so a death never costs you your XP bank.
Upgrade tanks before scaling up output, or the farm will back up when storage fills.