How do you make an 8-minute slow falling potion?

You can't. Redstone dust extends slow falling to 4 minutes, and that is the maximum — it is one of the few potions with no 8:00 variant.

Is there a Slow Falling II potion?

No. Glowstone dust has no effect on this potion. Slow falling has a single strength level in vanilla Minecraft.

Where do phantom membranes come from?

Phantoms — the flying mobs that spawn at night after three sleepless days — drop 0–1 membrane each, or up to 4 with the Looting enchantment.

Does slow falling protect you from the void?

Not by itself — the void still kills you. But falling slowly gives you precious extra seconds to throw an ender pearl or otherwise escape before you reach it.

How to Make a Potion of Slow Falling in Minecraft

Falling kills more Minecraft players than most bosses do, and the ender dragon knows it — her favorite trick is launching you skyward and letting gravity finish the job. A potion of slow falling is the direct counter: drink one and you drift down like a leaf, taking zero fall damage from any height. It is one of the stranger brews in the game, built on an ingredient dropped by a mob many players have never deliberately fought.

What You Need

Brewing stand — found in villages or crafted from cobblestone and a blaze rod.
Blaze powder — the stand's fuel, made from blaze rods.
Nether wart — grows in Nether fortresses; the base ingredient of nearly all potions.
Water bottles — glass bottles filled at any water source.
Phantom membrane — the special ingredient, dropped by phantoms.
Optional: redstone dust, gunpowder, or dragon's breath to modify the result.

Phantom membranes deserve a word, because they gate the whole recipe. Phantoms are the flying mobs that spawn at night once you have gone three days without sleeping, circling above players who have open sky overhead. They swoop in packs of two to four and drop 0–1 membrane on death, rising to as many as 4 with a Looting sword. If you sleep every night like a sensible person, you will have to deliberately stay up to stock this ingredient.

How to Brew It, Step by Step

Open the brewing stand and put blaze powder in the far-left fuel slot.
Place nether wart in the top ingredient slot and up to three water bottles below it.
Wait for the arrow to fill. Your bottles are now awkward potions — useless on their own, essential as a base.
Replace the nether wart with a phantom membrane and let the stand run again.
The bottles come out as potions of slow falling, each lasting 1 minute 30 seconds.

Extending and Modifying the Potion

The base brew is short, so most players modify it before drinking:

Redstone dust extends the duration to 4:00. That is the ceiling — unlike most potions, slow falling has no 8:00 version.
Gunpowder converts it into a splash potion you can throw. Aim it at the sky above you rather than at the ground, so none of the duration is wasted while the effect reaches you.
Dragon's breath turns the splash version into a lingering potion (1:00), leaving a cloud that grants slow falling to anything passing through it.
Glowstone does nothing — there is no Slow Falling II. The effect is binary: you fall slowly, or you don't.

When Slow Falling Actually Saves You

The ender dragon fight is the headline use. When she knocks you into the air, slow falling turns a fatal slam into a gentle descent, giving you time to aim for safe ground. It is equally valuable while exploring the outer End islands, where a missed ender pearl can mean a long fall toward the void — slow falling buys you the seconds to throw another pearl and save your gear from deletion.

Beyond the End, keep a bottle handy for tall build projects, deep cave drops while mining, and elytra mishaps near the ground. It will never be your most-used potion, but on the three occasions a year it matters, nothing else does its job. MLG water buckets are a skill; this potion is a guarantee.