A friend of mine and I are having an argument over the correct ruling over this situation.
NAP has a Chains of Mephistopheles in play. AP casts Brainstorm with one card in hand, it resolves, and immediately draws 3 cards, not understand how chains works.
My friend is arguing that because the player failed to discard his card because of chains before drawing his first card that the ruling is a GRV because the player failed to take an action that chains requires and AP would receive a warning.
I am arguing that because the player put a card into his hand when he should not have it would be a DEC and AP would receive a game loss.

Can anyone help us settle the argument?

Chains doesn't stop you from drawing the card, it just makes you discard first. The cards he drew are cards he is entitled to draw…they're just going to end up in his graveyard because of the chains effect.

What should have happened: Card in hand is A. Discard A, draw B, discard B, draw C, discard C, draw D, place D on top of library.

What he did: draw B, C, and D when the problem was noticed. We can fix this, so we randomly return 3 cards to his library.

GRV, warning.

Hey!

I'd like to share my opinion.
As Chain of Mephistopheles works, each draw from Brainstorm would be replaced by discarding a card, and after discarding a card the player would draw a card.
Therefore, the correct process of NAP would be discard one-draw one-discard one-draw one-discard one-draw one-put two cards from hand on top of library.
As the player draws three cards I think he commits GPE-GRV, because the player does not take into account the replacement effect created by the Chains of Mephistopheles.
As I see it, the player did not put cards into hand that shouldn't be there, but did everything in a wrong order, forgetting to discard in the middle. For this reason I believe that this action is not GPE-DEC.
If you discard cheating from the action of the player, I would say that the player commits GPE-GRV.

I hope mi opinion help you guys out!
All the best!

Originally posted by Elliot Garner:

because the player put a card into his hand when he should not have it would be a DEC

Nope, this is an example of

IPG 2.3
at the moment before … no other Game Play Error … had been committed

. There *IS* a GPE, so, as others have noted, we correct the situation, assess the Warning, and have him correctly resolve the Brainstorm/Chains interaction.

d:^D