The Oath of the Unseen allows you to customize the difficulty of each run. Each vow has a unique modifier that increases the challenges you face. If you played the first Hades, the Oaths are the new iteration of what was previously, The Pact of Punishment.
Some Vows are universal, like the Vow of Frenzy, which buffs the movement and attack speed of all foes. Other Vows, like Vow of Shadow, only affect designated enemy types.
In this guide, we will explain how to get every unlock related to the Oath of the Unseen and provide a brief overview of Fear, including our starting recommendations.
Good luck in becoming Night's Champion!
All Unlocks Explained
Unlock The Oath of the Unseen
To make the shrine appear in the Training Grounds of the Crossroads Malinois must first defeat Chronos one time. Upon unlocking the shrine you will then have the option to invoke any Vows you so please, other than the Vow of Rivals which are hidden until later.
Testaments of Night
Schelemeus will explain to you that brand new challenges await you, the Testaments of Night! To complete the challenge and earn Nightmare, you must defeat the pictured Guardian. Here we see 1 Fear above Prometheus. To complete the Testament and earn the reward you must do a run with at least 1 Fear, (any Vow worth 1 or more Fear), and defeat Prometheus in battle.
You will earn the Nightmare and unlock the next Testament, even if you do not make it all the through the final boss.
Gifts of the Veil
Schelemeus will also present you with the Gift of the Veil. You should see three statues covered by large cloths in the top right of the Training Grounds. After completing the required Fear level in both the Underworld and Surface, a new Statue will be unveiled to you.
Stone Statue: 8 Fear
Silver Statue: 16 Fear
Gold Statue: 24 Fear
(One more hidden Statue for after credits challenge) Major Spoiler, so we won't give details.
Fate Rerolls
You may notice, that in the middle of a run, if you hit the pause menu you you'll be given the option to, "Undo this Night." Doing so resets the run as if it never happened.
Without boring you with the exact details, every run is given a particular RNG seed. Normally, if you want to start a new seed you'd have to die finish the night return to the crossroads and then start a new run.
After completing the highest Testament of night you'll be given the option to Salute the Statue. and manually reroll the RNG seed before every run.
Vow Of Rivals
The Vow of Rivals is one of the most challenging of all Vows to complete. Each rank of the Vow of Rivals will be unlocked one at a time.
You'll need to defeat the unrivaled version of Guardians from both the Underworld and the Surface in order to unlock the next rank.
Fear Overview
The maximum possible number of Fear for a run is 67. Don't worry about that though, because as of the time of writing this guide, only 3 players in the world have been able to beat Hades 2 at 67 Fear.
When first trying to complete the Testaments of Night, these are generally considered to be the easiest Fear set up:
Vow of Time
Vow of Hubris (Depending on chosen Weapon Aspect)
Vow of Debt
Vow of Return
Vow of Menace
We strongly recommend avoiding the following Vows, until you get into very high Fear Totals:
Vow of Pain
Vow of Grit
Vow of Forfeit
Vow of Void (Most punishing Vow per Fear)
Now, it's important to remember that each rank can significantly increase the difficulty of achieving victory. For example, Vow of Time1, is basically 1 free fear, but Vow of Time3 will feel impossible until you learn how to optimize room clears and timer management.
Here's an example of a Fear loadout you can try when completing the 8 Fear Testament:
Unrivaled Difficulty
Vow of Rivals4 is extremely challenging, but also very fun. We recommend unlocking and playing all levels, but keep in mind if your specific goal is a higher Fear number Vow of Rivals is very punishing.
For the Underworld Vow of Rivals 1 & 2 fight against Hecate, then Scylla is very difficult, but the Rivals Cerberus is not that much harder.
For the Surface Vow of Rivals 1 & 2 are very manageable, but Rivals 3 against Prometheus is significantly harder.
Both Vow of Rivals4 are super challenging, so we recommend for taking those without Vow of Frenzy, Vow of Grit, or Vow of Pain activated.
Circe Vow Removal Boon
One special interaction with fear on the Surface route is that Circe may offer you a boon that will deactivate one random active vow.
Vow of Frenzy, which buffs the movement and attack speed of all foes. Other Vows, like 
Vow of Shadow, only affect designated enemy types.
