Equip Ygnium with Aspect of Eos:

Use cast to slow your enemies and keep them at a distance.

Use special to constantly deal surrounding damage.

Spam attack on the enemies from a distance.

Only dash forward to prevent enemies from respawning and repeat the cycle above.

Grab any boons/hammer upgrades that increase cast size, special or attack damage.

Ensure you have two boons that cause curses from different Olympians.

Vow of Pain Rank 1
Vow of Wards Rank 2
Vow of Frenzy Rank 1
Vow of Hordes Rank 3
Vow of Menace Rank 2
Vow of Return Rank 1
Vow of Fangs Rank 2
Vow of Shadow Rank 1
Vow of Forfeit Rank 1
Vow of Hubris Rank 2
Vow of Denial Rank 1
Vow of Rivals Rank 2

The most important Arcana to have:

Origination (+50% dmg to foes with 2 curse from diff gods)

The Furies (+30% dmg to foes in your cast)

The Sorceress (Attacks, casts and specials are 30% faster)

The Messenger (Casts make you invulnerable and you move 70% faster momentarily)

I only used one instance of Death defiance during my successful 32 Fear run, but having +3 would likely be helpful if you are struggling.

I did this with Ygnium and Rank 1 Aspect of Eos with ease. You do not need a fully upgraded weapon to beat Fear 32 Underworld.

The idea of the build is to not let any enemies touch you by using the cast to slow them down, special to constantly deal damage and just spamming attack from a distance.

Honestly, which gods you choose does not matter, as long as you are increasing special damage, making your cast bigger, and causing two curses.

Order of Keepsakes:

Erebus - Iridescent Fan (Hera)
Ideally grab Sworn Flourish to deal more special damage AND inflict hitch (1st curse) or Engagement Ring (casts inflict hitch)
(Sworn Flourish was my only Hera boon during my run)

Oceanus - Vivid Sea (Poseidon)
I grabbed Wave Strike to increase attack damage
then later grabbed Slippery Slope to inflict froth with wave strike (2nd curse)

Having two curses activates the Origination Aracana Card (you deal +50% damage to foes with at least 2 curses from different Olympians)

Fields of Mourning - Harmonic Photon (Apollo)
I wanted to get a daze effect but instead got Super Nova which increases cast size until they expire.
Then later grabbed Extra Dose which gives your attack a chance to hit twice.

Tartarus - Knuckle Bones (Odysseus)
The next Guardian loses 15% health and you take -10% damage from Guardians.

I brought Hecuba with me for the stun chance and increase magick! <3

List of boons I had in the end:

Wave Strike - Poseidon
Your Attacks hit foes with a splash that knocks other foes away

Slippery Slope - Poseidon
Your splash effects from Poseidon also inflict Froth, and Froth deals more damage

Sworn Flourish - Hera
Your Specials deal more damage and inflict Hitch

Rapture Ring - Aphrodite
Your Casts inflict Weak, and damage foes while dragging them toward the center

Sweet Surrender - Aphrodite
Weak-afflicted foes take more damage.

Ecstatic Obession - Aphrodite
As long as multiple foes are in an Encounter, automatically inflict Charm on 1 of them.

Tough Gain - Hephaestus
Whenever you take damage, shrug some of it off and restore 150 magick

Molten Touch - Hephaestus
Your Attacks and Specials deal bonus damage to Armor.

Security System - Hephaestus
At the start of each Encounter, you gain armor that lasts for 7 seconds.

Clean Coil - Daedalus Hammer
Lets you channel your Omega Special 20% faster and reduces its Magick cost by 10 Magick

Furious Blaze - Daedalus Hammer
While you Channel your Attacks, you move and fire 20% faster

Super Nova - Apollo
Your Casts expand in size until they expire.

Extra Dose - Apollo
Your Attack has a chance to hit 2 times.

Racing Thoughs - Hermes
Your moves are faster.

Nitro Boost - Hermes
Your Sprint is 15% faster and gives you a barrier that ignores instances of damage.

Old Grudge - Hades
In your confrontation, Chronos takes a burst of damage after the first 3 seconds.

This is my first ever guide! Hope its helpful to you!
Moonlight guide you! <3