That's the question, When does Cauldron of Blood trigger? or Where does the "this zone is attacked" take place?

It's not the same declare zone to attack, than attack it, the same about declaring attackers, and the step where it takes place will determine if a unit is killed before it is assigned, before it assigns damage or if it will be corrupted via Shrine to Nurgle.

Thanks for answers.

Card text for Cauldron of Blood:

Kingdom. Forced: When this zone is attacked, deal 1 damage to one target attacking unit.

Here's my interpretation: when attackers are declared during an attack against the kingdom, CoB deals 1 damage to one target attacking unit.

• The damage from the CoB is non-combat damage.
• It's before the attacker assigns damage so if the CoB damage is enough to destroy the attacker, the attacker will not deal damage in combat.
• Post-errata Shrine to Nurgle only triggers on damage in combat, so the attacker will not become corrupted if you also have a Shrine to Nurgle.
• Note that it's a forced effect, so you can't respond to the CoB damage assignation with an action.

Thanks for reply.

I just was wondering when it takes place, because "this zone is attacked" is not a clear trigger with a 5 steps combat phase. It's obvious that it's taking place between phase 2 and 5, because needs attacking units to target. Probably it's as you say, nevertheless i'm asking James via mail.

Declare zone, declare attackers, that zone is now being attacked. No other point in the 5 steps adds any parameters the card is checking on so it makes no sense for it to trigger any later than Step 2, IMO. Admittedly getting official confirmation on this is not a bad idea, though I can't see any coherent argument about why it should trigger later. Defenders, assignment of combat damage, application of combat damage are all unnecessary, and truthfully do not even have to take place in combat. I think we would all agree that after attackers are declared I could play a tactic from my hand that buffed, debuffed, or even damaged an attacking (or all attacking) units. Why would this card need to trigger at a later point?

dormouse said:

To be considered combat damage and interact with Shrine to Nurgle. But no, James said that as you all supposed, it triggers inmediately after attackers are assigned

StN has been errata'd and now triggers only on combat damage.

Tobogan said:

This card works like counter-attack. For all the rules lawyers, I didn't say it was "counter-attack" - I said worked like.

Dark Elves are very good at this.

Counterstrike? Yes it is very similar, except it triggers first and can be canceled, but strategically it can be thought of as Counterstrike in a Support form.