Okay, this is probably going to be long-winded, but I just want to make sure this ruling is correct, as this situation may occur in my EDH group. I would like for a Rules Judge to make sure this is correct, and I will post the individual card rulings for each card.
Situation is that I have {Nekusar, the Mindrazer} or other card draw engine in play, {Chains of Mephistopheles} and {Teferi's Puzzle Box} in play. My opponent has, let's say 3 cards in hand.
It is the start of my opponent's draw phase.
1) They draw their initial card and proceed to attempt to draw the extra card. 4 cards in hand.
2) Chains replacement effect kicks in since it is not the first draw they are attempting in their draw step. Since they have cards in hand, they are forced to choose and discard a card, then draw a card. 4 cards in hand.
3) At this point, Puzzle Box's effect kicks in and forces them to put their hand (4 cards) on the bottom of the deck and then attempt to draw the same amount of cards. (4 cards)
4) Since we are still in the draw step, Chains replacement effect kicks in. Since they are attempting to draw 4 cards, Chains treats multiple card draws as that number of single draw 1 actions.
5) Since there are no cards in opponent's hand, Chains other replacement effect kicks in and they are forced to mill 4 cards with no draws.
Based on my understanding, this three card combo will basically reduce every player to 0 cards by the end of their draw steps. Is this correct? That is my question. I'm not worried about the damage dealing portion of Nekusar.
Individual Card Rulings:
{Nekusar, the Mindrazer}
None on Gatherer. Inferred from {Howling Mine} and {Underworld Dreams}
10/4/2004: The additional draw is separate from any other draw during your draw step. It happens when the triggered ability resolves.
4/15/2013: The triggered ability is put onto the stack after you have already drawn your card for the turn.
10/4/2004: If multiple cards are drawn at once, this card triggers once for each card drawn.
10/4/2004: In a multi-player game, it affects all opponents.
{Chains of Mephistopheles}
10/4/2004: The effect is cumulative. If there are two of these on the battlefield, each of them will modify each draw (after the first one if during the draw step), and will cause the player to discard or to "mill" a card from their library. As they resolve in order, the player must discard if possible. Once the player fails to discard and instead "mills" a card, all further effects of additional Chains of Mephistopheles will not do anything. This is because the "mill" also replaces the draw effect and the player is no longer drawing a card. You handle them in order. Each one makes you discard first and then continue or else mill a card and lose the draw.
10/4/2004: Cards which are drawn as a cost are affected by this card because replacement effects can alter the payment of costs.
9/16/2007: If a spell or ability would cause a player to draw multiple cards, this is treated as a number of individual "draw one card" actions. Apply the effect of Chains of Mephistopheles to each one.
9/16/2007: A player's normal card draw on his or her turn is exempt from this effect. All other draws will be affected.
9/16/2007: Here's what happens when Chains of Mephistopheles replaces a player's draw: -- If that player has at least one card in his or her hand, he or she discards a card and then draws a card. -- If that player's hand is empty, he or she puts the top card of his or her library into his or her graveyard. The player doesn't draw a card at all.
{Teferi's Puzzle Box}
10/4/2004: You do your normal draw before this ability is put on the stack.
10/4/2004: If you have more than one of these, each effect triggers separately.
Thank you for your time.