This situation was proposed on Storm Boards. Imagine that you're in a tight game one against Tempo Thresh playing Next Level Storm. You resolved a Meditate on turn two with the help of a Chrome Mox and now you're ready to act again. Your opponent wasted your Badlands with one of their turns while playing a Tarmogoyf. You're at 15 due to fetches and Tarmogoyf. Your hand is decent after your draw step, and your Brainstorm produces a hand of: Duress, Volcanic Island, Lotus Petal, Dark Ritual, Cabal Ritual, Ad Nauseam, and Lion's Eye Diamond x2. You cast Duress with your Chrome Mox. You have Infernal Tutor on top of your library with a Brainstorm hiding underneath the tutor. Three lands, Meditate, and Brainstorm are in your graveyard. You have Underground Sea tapped (Brainstorm), Chrome Mox (imprinting a Cabal Ritual) tapped (Duress), Bayou untapped, and a Sensei's Divining Top (untapped) in play. (Picture of the Situation)

Your Duress reveals an opponent who has Force of Will, Lightning Bolt, Fire/Ice, and Spell Snare in hand to go with Tropical Island, Volcanic Island, and Flooded Strand untapped in play. There is a tapped Tarmogoyf (3/4) on their side as well. What should you take? It has to be Force of Will right? I don't think so. Let's look at why.

You have four choices for Duress, but if you don't want to leave your opponent with two counters (your need to resolve a bomb and you only have two), Lightning Bolt isn't a real option. So Force of Will, Fire/Ice, and Spell Snare are your options. To figure out the card to take, let's look at what our plays can be.

We have "the obvious" option of all-in Ad Nauseam with a Infernal Tutor off the top if we don't get Ad Nauseam to resolve. To do this we just play out our hand and we either get to Ad Nauseam to draw a bunch of cards or we get to Infernal Tutor for a lethal Tendrils (if the opponent plays a spell you will be guaranteed at least 9 spells + Tendrils this turn by playing out your hand). This will probably work, but what if we have some bad flips?

Say our Ad Nauseam resolves and we don't draw another Duress or bomb (we know we have Brainstorm due to the top 2 cards from the previous Brainstorm). We're at 15 life and the opponent has a Lightning Bolt in play. That means we're working with effectively 9-11 life (3 from Bolt, 0-2 from Fire, 1 because we need to survive Ad Nauseam). It's actually worse than this though. We are working with 7-9 life because our top two cards are known (6-8 life if you don't activate SDT with Ad Nauseam on the stack after breaking LEDs for mana, but then we both know you're good enough to see that play right?). So we can spend 7-9 life after we draw SDT and Brainstorm to leave us at 4-6. This is even worse than it sounds because while we have 9 life to spend, going to 4-6 or less life is a game loss. In actuality, we should be stopping at 6-10 life (depending on how aggressive you are) to avoid flipping a 2+ CMC at 5/7 life and autolosing to our opponent's burn. This brings our window of usable life total to between 5/3 (stopping at 8-10) and 7/5 (stopping at 6-8) life. Our average CMC with NLS is slightly under 1, so that should give us roughly 6 cards on top of IT/SDT and Brainstorm with just Lightning Bolt and 4 cards with Bolt + Fire/Ice.

Does this knowledge change your opinion about how to play out our hand? It does for me. There is a significant chance that resolving Ad Nauseam will fail to win the game for me (increasingly so if my opponent still has Fire/Ice in hand). If that's the case, then I want my opponent to Force of Will my Ad Nauseam so I can safely cast Infernal Tutor. To make this happen, first we need to make sure we don't have any choking points prior to casting Ad Nauseam.

Will an opponent countering something unexpected affect our play? If an opponent counters Lotus Petal, we still have (U/R) and (B/G) available with which to play our rituals. If the opponent counters Dark Ritual, we have Lotus Petal and Volc Island to play Cabal Ritual. If an opponent counters a Lion's Eye Diamond, we still would make at least 6 mana with which to SDT into IT into Tendrils. We don't have a choking point which means we want our opponent to Force of Will something. This means we're down to choosing between Fire/Ice and Spell Snare. If we take either of these, the opponent would be forced to choose between casting Force of Will and whatever card we left them with (Force pitches the remaining blue card).

Outside of Force fodder, Spell Snare has two applications to our hand right now. It can counter Cabal Ritual or the Infernal Tutor on top of our library. Fire/Ice can be used to make us draw expend Sensei's Divining Top when we don't want to, to add extra damage to make Ad Nauseam worse, or to cantrip against something that isn't Sensei's Divining Top (Ice will likely be countered by the game rules if they target this) to try to draw something like Stifle, Daze, or Spell Snare.

If we leave the opponent with Spell Snare, the worst our opponent can do is counter one spell and burn us for three. If we leave the opponent with Fire/Ice, they can burn us for 3 and either counter a spell or burn us for an additional 2. Ad Nauseam is pretty good bait for Force of Will, but an opponent who has 5 points worth of burn might very well be tempted to hold on to it so as to affect your flips in hopes you don't draw well (either being forced to stop due to the threat of burn or that you don't draw another protection spell/tendrils of agony). I believe leaving the opponent with the fewest options is correct here and I would recommend that you take Fire/Ice with Duress.

Now that we know what to take with Duress, how does the rest of it play out? Does it matter? Well, yes it matters very much. Even with more life points to work with and the power of Ad Nauseam being what it is, an opponent doesn't have to counter it or any other spell we play previous to it. This means our play needs to be tight enough to let us have the maximum chances if we do resolve Ad Nauseam.

The first spell you should play is Dark Ritual followed by a threshed Cabal Ritual if Dark Ritual resolves. Why not a land or Lotus Petal? We know our opponent has Spell Snare, Force of Will, and Lightning Bolt. Lightning Bolt becomes irrelevant if our opp uses either blue spell because then we get to resolve Infernal Tutor (our goal). If we appear to be at a choking opponent (B floating, needing Cabal Ritual to continue our turn), the opponent might gamble that countering a ritual effect will save them from what is coming up next. We want our opponent to think we are short on mana (with Cabal Ritual on the stack we would have 5 cards in hand) so we get a free shot at Infernal Tutor.

If your rituals resolve, Lion's Eye Diamonds, Lotus Petal, and Volcanic Island can be played. Assuming these all resolve, you'll want to play Ad Nauseam and before passing priority you need to break at least one Lion's Eye Diamond for BBB and then activate Sensei's Divining Top to draw your Infernal Tutor. This will leave you with BBBB in pool along with Lotus Petal and Volcanic Island in play while holding a card unknown to the opponent. You still have another Lion's Eye Diamond to make Infernal Tutor hellbent and you have appropriate mana to cast Burning Wish, Brainstorm + Mystical Tutor, or Tendrils of Agony should you actually draw them. Your opponent will probably Force of Will the Ad Nauseam at which point you win.

Bonus Exercise:

Assume he doesn't. While you're flipping, what are you looking for? Survery the situation: You have Infernal Tutor, Sensei's Divining Top, and Brainstorm known in hand. There is RBBB in pool with Lotus Petal, Lion's Eye Diamond, and Volcanic Island available.

- Tendrils of Agony is an autowin.
- Duress will win the game by taking Spell Snare.
- Mystical Tutor will win the game by forcing the opponent to either counter it or Sensei's Divining Top (the threat of Tendrils is enough for this) letting you win with Infernal Tutor -> Tendrils.
- Burning Wish can find Tendrils of Agony so it has to be stopped.
- Infernal Tutor #2 will also due the trick if you can scrounge another mana (you can Brainstorm it away, replay Sensei's Divining Top and then are able to cast both Infernal Tutors with hellbent).
- Doomsday (assuming you can cast it at 8 or more life) (put Tendrils on top if it resolves) with an extra mana. If this or Sensei's Divining Top are countered, you get to play Infernal Tutor with hellbent into Tendrils.