The opponent chooses whether he or she sacrifices a creature, pays 3 life, or allows you to draw a card. That player can't make an impossible choice, such as sacrificing a creature while he or she controls no creatures.

If there are no legal targets to choose, perhaps because all your opponents have hexproof, the ability is removed from the stack with no effect. You won't draw a card. This is also true if the target opponent becomes an illegal target in response to the ability.

If X is 0, Torment of Hailfire resolves with no effect.

While resolving Torment of Hailfire, your opponent chooses a card to be discarded without revealing it, chooses a nonland permanent to be sacrificed, or chooses to do neither. Then that player discards that card, sacrifices that permanent, or loses 3 life, then repeats this process if it hasn't been done X times yet. Your opponent can always choose to lose 3 life, even if he or she has cards to discard or nonland permanents to sacrifice.

Each repetition through this process is done separately. If an opponent sacrifices a creature with an ability that triggers when another creature dies, for example, it will see creatures that are sacrificed before it, but not those are sacrificed after it.

State-based actions aren't checked in between repetitions of this process, so the game state may be a little unusual while making the choice. For example, a player may sacrifice a creature and then later sacrifice an Aura that was attached to that creature.

In a multiplayer game, each opponent in turn order makes his or her choice once, then all of the actions occur simultaneously, then they repeat this process if it hasn't been done X times yet. Opponents will know choices made by earlier opponents when making their choices, although a card chosen to be discarded this way isn't revealed until it's discarded.

In a Two-Headed Giant game, Torment of Hailfire causes both opponents to sacrifice a nonland permanent, discard a card, or lose 3 life X times. Your opponents can choose the same torment or different ones each time.