First of all, why would you ever want to cast Doomsday and then pass the turn? The answer is simple: when you can't win otherwise. Pass the turn piles help out when you can't win right now, because you lack mana and/or draw effects, but you can't afford to wait much longer either. It should be clear that pass the turn piles are practically never a very desirable plan. When you make decisions like whether to keep a hand or not, or when to cast your cantrips, going for a pass the turn pile should serve as a last resort. The risks involved in paying half your life rounded up and passing the turn are not to be underestimated.

In Legacy, discard is one of the most common strategies for disrupting your opponents plan. Therefore, many decks try to use discard to prevent us from winning the game before they do. One of the main uses of pass the turn piles is to become immune to discard. If you can't win right now because you still lack some resources, but you can cast Doomsday and dump other cards, like Lion's Eye Diamond or Conjurer's Bauble on the table, you may be able to setup a win for next turn without giving your opponent another window to discard any of your precious cards.

In some other (uncommon) situations building a pass the turn pile may be your best shot at winning the game any time soon. For example, when you lack a draw effect to draw in to your pile, but have everything else, pass the turn piles may be an out. How you managed to end up in this situation is a good question, in general, it's not a good idea to keep a hand without sufficient filter/draw spells or use your cantrips too aggressively and be a left with a Doomsday and no draw effect.

Now that we've made clear that pass the turn piles are a last resort, but may serve as an out in some situations, we are ready to get started:

There is some good reason that you are going for a pass the turn pile rather than winning this turn, either you lack resources or you have to fight through some form of hate. Let's first talk about building pass the turn piles because we lack resources, such as a draw effect or mana. We'll focus on playing around/through hate later.

Consider the following (intentionally) bad example: you cast Doomsday, but lack a draw effect and therefore build:

-> IU, LED, LED, GP, BW(ToA)         UU (2)      6 Storm

Next turn, for only UU you can draw and cast Ideas Unbound, followed by 2 Lion's Eye Diamonds and Gitaxian Probe into Burning Wish for Tendrils of Agony for 6 storm. Although the mana cost of this procedure is very low, the storm count is a bit of a disappointment. Fortunately, it's easy to increase the storm count from this point on. If you have 1 more mana you can build IU, LED, GP, CB, BW as a pile for 7 storm for example. Together with some cards in hand to play out and some self-inflicted damage from your opponent's fetchlands, that might just be enough.

There are however some more solid ways of winning the game even after passing the turn, that still work if passing the turn is primarily an anti-discard plan. The ones I will talk about in more detail are using Laboratory Maniac, Time Spiral, and Doomsday.

Pass the turn piles with Laboratory Maniac

Laboratory Maniac enables some very mana efficient pass the turn piles that may offer an out in situations where no other lethal pile would. When you have no other cards in hand or play, for example because you've used Lion's Eye Diamond to pay for Doomsday, the simplest piles are:

-> IU, CB, LED, GP, LM              1UU (3)     2 life
-> TW, LED, GP, GP, LM              1UU (3)     4 life

The following piles are even cheaper for when you have an extra draw effect or a LED.

LED:
-> GP, IU, CB, DR, LM               B           2 life
-> GP, [TW/AoI], LED, GP, LM          0         4 life

GP in hand:
-> LED, IU, DR, CB, LM              B           2 life
-> LED, IU, LP, GP, LM              1           4 life
-> LED, [TW/AoI], LED, GP, LM         0         4 life

CB in play:
-> LED, IU, DR, CB, LM              B           0 life
-> LED, [TW/AoI], LED, GP, LM       0           2 life

Instead of using Lion's Eye Diamond to pay for Ideas Unbound we can also include some other card into the pile, to for example play through some card in the opponent's hand. The mana cost for including another card depends on the location in the pile. There's also a trade-off between life and mana cost.

GP in hand:
-> Silence, IU, LP, GP, LM          W+2UU       4 life
-> Silence, TW, LED, GP, LM         W+1UU       4 life
-> Silence, AoI, LED, GP, LM        W+2R        4 life
-> LED, IU, Silence, GP, LM         W+2         4 life

LED:
-> GP, IU, Silence, GP, LM          W+2         4 life
-> GP, TW, Silence, GP, LM          W+2U        4 life

I've listed Silence because of its distinct mana cost, but you can obviously replace the Silence with any other card. Examples are Duress, Karakas, or perhaps even a Massacre.

For all Laboratory Maniac pass the turn piles, you can replace the card that draws from an empty library in the Doomsday pile with Chromatic Sphere and increase the mana cost accordingly.

Time Spiral Pass the Turn Piles

The cost listed in square brackets [..] is assumingly paid for by the lands that are untapped by Time Spiral.

A simple example of a pass the turn pile that uses Time Spiral is as follows:

-> IU, LED, LED, BW(TSP), BW(ToA)       UU+1R+[1R] (4)   9 Storm

Actually, if you have no other cards in hand or your post-Doomsday graveyard resolving Time Spiral will kill you. The Doomsday you've cast to build this pile typically ends up as the only card in your graveyard, with 5 cards in your pass the turn pile this adds up to 6. However, the Burning Wish used to wish for Time Spiral exiles itself, so that's only 5 cards. That's is why you need at least 2 random cards in your hand or post-Doomsday graveyard to not kill yourself. Given that you have 2 extra cards that you may cast before and after the Time Spiral, as long as they don't exile themselves or other cards, you might be able to up to storm to well beyond 10. Also note, that the listed cost assumes that you can produce 1R with the lands that you untap with Time Spiral.

Executing a Time Spiral pass the turn pile will become much easier if you have some extra resources, like a Lion's Eye Diamond or a Conjurer's Bauble. If you have both a pass the turn pile would not be necessary unless you're fighting through hate. Considering the following piles:

LED in play + 1 card:
-> IU, LED, LED, BW(TSP), BW(ToA)       2UU+[1] (4)      10 Storm

CB in play + 1 card:
-> IU, LED, LED, BW(TSP), BW(ToA)       2UU+[1] (4)      10 Storm
-> LED, IU, LED, BW(TSP), BW(ToA)       3R+[1]  (4)      10 Storm

These piles are actually a bit mana-inefficient. It is not possible to turn additional draw effects into mana, because we don't have enough room in the pile and the whole procedure is actually quite expensive mana wise: IU=2 + BW=2 + TSP=6 = 10 mana, with another 1 post-TSP. As the 2 Burning Wishes and the Ideas Unbound already take up 3 spots, we only have room for 2 Lion's Eye Diamonds and these can be easily drawn by Ideas Unbound, extra draw is not going to help. Note that the CB piles assume that you play LED, LED, CB post-Time Spiral, crack both LEDs and re-draw Burning Wish with CB from your empty library.

This is of course no longer true if you already have Ideas Unbound or Burning Wish, as you don't have to include them in the pile. Ideas Unbound in hand is not that great as you will be very vulnerable to discard. Having a Burning Wish in your hand or post-Doomsday graveyard is better. You can use it to wish for Tendrils after Time Spiral, and fill up its slot in the pile with another Lion's Eye Diamond. Examples:

CB in play + BW in hand or graveyard:
-> LED, IU, LED, LED, BW(TSP)           R+[1]  (1)      12 Storm

CB in play + IU in hand:
-> LED, LED, LED, BW(TSP), BW(ToA)      UU+[1] (2)      12 Storm

Double-Doomsday Pass the Turn Piles

Compared to Time Spiral pass the turn piles, these are more expensive in terms of life, but have different requirements in terms of mana and cards. You can perform a Time Spiral pass the turn pile with 2 random cards if you can produce 4 mana on the next turn. With double-doomsday pass the turn piles you should remember that in general you need 1 specific card and 3 mana. I will leave whether or not we should regard this as either less or more expensive up for discussion.

To convert a TSP pass the turn pile into a Doomsday pass the turn pile, we replace a Burning Wish in the pile with a Doomsday. The problem is that we also need some means of drawing into our second Doomsday pile. If you did not have a Conjurer's Bauble in play already, you have to replace some card in the pile with a draw effect. Preferably Conjurer's Bauble if using Ideas Unbound or in general when you're too low on life to use Gitaxian Probe. Notice that you can safely use Gitaxian Probe as a stored draw for LED if playing Three Wishes or Act on Impulse. Most importantly, remember that in general you need a LED and three mana next turn and you'll be able to figure to pile out on the spot.

LED in play, PTT:
-> [TW/AoI], LED, GP, DD, BW        1UU/2R (3)         9 Storm
-> [TW/AoI], LED, LED, BW(ToA), X

LED, CB in play, PTT:
-> IU, LED, GP, BW, BW(DD)          1UUR   (4)         10 Storm
-> IU, LED, LED, GP, BW(ToA)

Pass the Turn CB piles

Conjurer's Bauble can be used to increase storm despite an apparant lack of card resource. Remember that when you have a CB in play, one in the graveyard and no cards in your library you can loop them for the cost of (1) mana.

LED in play, PTT:
-> IC, LED, CB, CB, ToA                 BBB+X (3+X)      9+X Storm
-> CB, IU, LED, CB, ToA                 2+X              5+X storm
-> CB, [TW/AoI], LED, CB, ToA           1+X              7+X Storm

In the above example, what looks like a poor setup of only five spells can be used to enable a greater storm count. In the above example we cast IC (1) using the mana we used to cast DD the previous turn. We hold priority and crack LED for BBB. We then draw LED, CB, CB, ToA. We play LED (2) and use BB to cast both CBs (3,4). We then activate LED for BBB discarding ToA. We activate our first CB targeting LED, drawing it from our empty deck. We cast LED (5). We now have BBBBBBB in our mana pool. We can use this with CB to activate CB targeting the CB in the graveyard and loop them playing them again and again until we only have BBBB in our mana pool. In this base example this is for three loops (6,7,8). We can then use the final one to target ToA and cast it for 9 storm.

Summary

  1. You don't always have to win the turn you cast Doomsday
  2. Pass the turn piles are effective when low on resource (cards or mana)
  3. PTT piles do leave you susceptible to hand attack
  4. There are tricks you can use to ensure you can build up enough storm so you don't always have to rely on LM