Can only review this from the perspective of playing ||Agnes, but boy, is this card a doozy for her!

First, lets break down what this card does.

• It helps with the actual test numbers. I don't need to wax lyrical on why this is useful. Bigger numbers = better tests. It's a little more narrow, in that it only helps with Spell event tests, but given they're typically higher impact, getting them to 'go off' more reliably is always a bonus.
• It helps beat the Chaos bag. Sometimes, this is just making sure you don't draw the auto-fail. Sometimes it's two bites at the apple for your Hail Mary. Spell events are generally costly, and for the low price of one horror, you can turn off the swingiest token in the bag, ensuring you get the bang for your buck.
• It helps maximise your and minimise your . We've all been there. I need two clues with my Read the Signs, and I'm testing 7 vs 1. Draw 3 Bless tokens and a +1. Almost feels as bad as drawing . Flipside, when you're making these huge tests, you can deliberately fish for Curse tokens to try and 'purge the bag'.
• You can use it to fish for bonus effects. This is, for the most part, limited to Spectral Razor, Ethereal Form, Read the Signs and Banish within spell effects, but can be useful for triggering your other assets, like Ritual Candles or Paradoxical Covenant, or even just fishing for the .

So, it boils down to an amalgam of Holy Rosary and Grotesque Statue, without the soak, and strictly only for spell events. In other decks, this would be a little limiting, as your spell events deplete. For ||Agnes, this just doubles down on what you're already good at. You're already needing to set up to weather the damage you take from your own ability, and potentially having to soak Dark Memory.

For ||Agnes, I think that Sutra has a very strong and positive effect on how your deck functions. Are there better cards? Certainly, but for 2 XP, you get a lot of slot compression, particularly around your neck slot, which is heavily contested between Hallowed Mirror and Heirloom of Hyperborea. Bonus points when paired up with Prophetic so you can bump your spells even more!