When to use Shard/The line when action becoems to expensive after announcement

Situation:
I control a card that reduces blood cost (Shard/the line)

I announce an action that costs 2 blood, with a vampire that has 2 blood.

I play an action modifier that costs 1 blood.

The Vampire now doesnt have enough blood to pay for the action, if it reaches resolution.

Do I have to use Shard/Line immedeatly, to keep the action legal, or can I opt to use it as soon as reolution hits, to make it cheap enough to pay for the action, to keep it from fizzeling?

Hobbesgoblin wrote:

Situation:
I control a card that reduces blood cost (Shard/the line)

I announce an action that costs 2 blood, with a vampire that has 2 blood.

I play an action modifier that costs 1 blood.

The Vampire now doesnt have enough blood to pay for the action, if it reaches resolution.

Do I have to use Shard/Line immedeatly, to keep the action legal, or can I opt to use it as soon as reolution hits, to make it cheap enough to pay for the action, to keep it from fizzeling?

The Line

Cardtype: Master
Unique location.
Lock to reduce the cost of an action card played by a vampire you control by 1 blood (this location is not locked if that card is canceled as it is played). Any vampire can steal this location as a action.

The Shard, London

Cardtype: Master
Cost: 2 pool
Unique location.
If you have the Edge, you can lock this card to reduce the cost of a card you play by 2 pool or blood. Vampires can steal this location as a action; Ventrue get +1 stealth during that action.

To my understanding the ability to pay for an action is checked at two stages
1) when announcing the action
2) when the action reaches resolution i.e. is successful (is unblocked) prior to resolving

The answer is no.

If one was able to pay for the cost (2 blood) when announcing the action and later use any of the blood to pay for something else (modifier -1 blood) one doesn´t have to use e.g. The Line immediately and the action doesn't fizzle immediately either as the ability to pay the cost is not continuously checked (opposite to eg readiness of the minion which is continuously checked throughout the action), the action, in this case, would only fizzle because of the inability to pay its cost when the action reaches resolution if you choose not to use The Line.

One needs to be able to pay the cost when announcing (basically saying how much is from what sources) but one doesn’t commit to that it will be paid as announced, how one actually pays one gets to decide at the time the payment is done. Note that if counters and effects from cards e.g. Ravnos Cashe, The Line, The Shard, etc. are part of the announcement of how the cost will be paid one cannot let the action fizzle by choosing not to use them….while if it wasn’t part of the announcement one isn’t forced to use them and can let the action fizzle.

Ankha please confirm if the above is correct.

I think it's the latter - the action is successful when all block attempts were unsuccessful, and then the cost of the action is paid, so you should be able to decide up until that moment.