I did have Perseverance wrong. You cancel four regardless.

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Greetings,

Perseverance would cancel up to 4 of the damage/horror just assigned to you, as long as any of that damage/horror would defeat you.

Perseverance says: "Fast. Play when you are assigned damage and/or horror that would defeat you. Cancel up to 4 of that damage and/or horror.”

It’s important to note that the first part just notes the timing and conditions under which the card can be played, whereas the second part is the actual effect.
Let’s say you have 2 health remaining and are assigned 4 damage. Perseverance can be played in this instance, because the 4 damage you are assigned would defeat you. You then resolve the effect, which is to cancel the 4 damage. The effect does not say to cancel only the damage in excess of your remaining health; it just says “that damage,” referring to the damage that was just assigned to you.