Seeds of Agony (Red)

You may play this from your banished zone.

The next attack action card with cost 2 or less you play this turn gets "When this attacks, deal 1 arcane damage to target hero."

Go again

Blood Debt

Rulings

From the Monarch release notes

You choose the target you want to deal 1 arcane damage to at the time you play an attack action card with cost 0/1/2 or less.
The attack action is the card that does the arcane damage.
With the release of the comprehensive rules on May 4th 2021, the card text of Seeds of Agony been errata’d to “The next attack action card with cost 0/1/2 or less you play this turn gains “When you attack with this, deal 1 arcane damage to target hero.”” (Seeds of Agony is the only card in Monarch that functionally changes with the release of the comprehensive rules. Other cards do have updated text but their functionality is not affected.) The errata to Seeds of Agony is effective immediately.
If you play multiple Seeds of Agony followed by an attack action card, it will have multiple instances of “When you attack with this, deal 1 arcane damage to target hero.” It will be considered multiple triggers therefore each one is it’s own source. This is relevant for preventing damage from arcane barrier. For example if you have an attack action with 2 instances of “When this attacks, deal 1 arcane damage to target hero” it will require arcane barrier 1 and two resources to fully prevent this.
If you play multiple Seeds of Agony followed by an attack action card, it will have multiple instances of “When you attack with this, deal 1 arcane damage to target hero.” It will be considered multiple triggers therefore each one is it’s own source. This is relevant for preventing damage from spellvoid. For example if you have an attack action with 2 instances of “When this attacks, deal 1 arcane damage to target hero” you will not be able to prevent both with spellvoid 2. (You can use two instances of spellvoid 1 to prevent both.)

Keyword notes

Go again - Go again allows multiple actions to be played in a turn when usually playing an action with use up your action point, and therefore end your turn. A card with go again gives the controller of that card or activated ability 1 action point when it resolves.

When an action with go again resolves, its controller gains 1 action point.
Multiple instances of go again on the same card or activated ability do not stack. If a card or activated ability has multiple instances of go again when it resolves its controller gains 1 action point only.
If an action with go again does not resolve, its controller does not gain 1 action point.
You cannot reveal a card with no to Belittle. The card must have a value to its power that is 3 or less. (0 is a value)

All keywords

Blood Debt - Blood Debt is a new keyword existing on Shadow cards. Shadow cards can inflict a loss of life to access a greater power. At the end of your turn, you lose 1{h} for each blood debt card in your banished zone.

You only lose life at the end phase. Players do not have priority during the end phase.
If you have multiple cards with blood debt, you lose 1 for each instance of blood debt at the end of turn.
Only face-up cards banished with blood debt counts and will lose you . Face-down banished cards have no effects or stats.