If you have cards in play with an ability that reads

"You may initiate an additional ... challenge during the challenges phase."

what happens if some of these cards leave play?

Option 1:

When initiating the challenge you choose which challenge it is.

Option 2:

When initiating the challenge you must have enough cards in play to allow the challenge.

Example:

1. You have Khal Drogo in play

2. You initiate and resolve your first military challenge

3. Your opponent kills Khal Drogo

Are you allowed to initiate another military challenge, because you say the first challenge was the additional challenge from Khal Drogo and you still have your one default challenge?

No. When you want to initiate that military challenge, the game sees that you have already initiated one and have no permission for an additional one. In other words, you have to use the default one before the additional one(s).

Yup, even with multiples on the board (e.g. Drogo AND the plot), the game is always checking whether you have sufficient permissions to initiate another challenge.

INitiate challenge 1

Are you allowed to initiate another? Yes - you have one or more (Drogo + Plot) effects that allow for additional challenges

Initiate Challenge 2. Drogo dies during the challenge.

Are you allowed to initiate another? No - you do not have 2 effects that allow for an additional challenges.

Hand of the King

You may initiate an additional challenge during the challenges phase, against a different opponent.

At the moment there are no other cards granting an additional power challenge. But what if ...

• Initiate challenge against opponent A
• Initiate challenge against opponent B
• Against what opponents can I initiate my third power challenge? Anyone except A? Anyone except A or B?

Let's just hope there will be no more cards with additional power challenges. I believe they would be game breaking.

I could see that depending on the wording of the hypothetical card in question.

Hand of the King

You may initiate an additional challenge during the challenges phase, against a different opponent.

At the moment there are no other cards granting an additional power challenge. But what if ...

• Initiate challenge against opponent A
• Initiate challenge against opponent B
• Against what opponents can I initiate my third power challenge? Anyone except A? Anyone except A or B?

Let's just hope there will be no more cards with additional power challenges. I believe they would be game breaking.

The short answer is that both effects are active at the same time and do not conflict, so the limitations put on your ability to initiate POW challenges are going to apply to all POW challenges you try to initiate. You will have to initiate each POW challenge against a "different" opponent.

The thing to remember is that "may initiate an additional challenge" effect do not create new challenge for you, so you are not dealing with a question of "which effect created the challenge I am trying to initiate right now?" Rather, these effects change the restrictions on how many times you can go through the "initiate challenge" loop as the active player. They are lasting and/or continuous effects that change the basic rules of the game, so if they are active, they apply to initiating the challenge. You cannot "selectively apply" the "additional challenge" modifiers.

The easier example to see is probably this:

• Card A: You may initiate an additional MIL challenge this challenge phase.
• Card B: You may initiate an additional MIL challenge this challenge phase (maximum of 2).

The maximum is going to apply, no matter how may "additional challenge" effects you try to play, or in what order, right?