Hell's Caretaker
3B
Creature - Hell's-Caretaker
1/1
T, Sacrifice a creature: Return target creature card from your graveyard to play. Play this ability only during your upkeep.

409.1. Playing a spell or activated ability follows the steps listed below, in order. If at the end of playing a spell or ability a player was unable to comply with any of the steps listed below, the game returns to the moment before that spell or ability was played (see rule 422, “Handling Illegal Actions”). Players can’t begin to play a spell or ability that’s prohibited from being played by an effect. Announcements and payments can’t be altered after they’ve been made. Playing a spell or ability that alters costs won’t do anything to spells and abilities that are already on the stack.
Some spells and abilities specify that their controller’s opponent does something the controller would normally do while it’s being played, such as choose a mode, choose targets, or choose how the spell or ability will affect its targets. In these cases, the opponent does so when the spell or ability’s controller normally would do so. If the spell or ability instructs both players to do something at the same time as it’s being played, the spell’s controller goes first, then his or her opponent. This applies to all parts of rule 409.1.

409.1a The player announces that he or she is playing the spell or ability. It goes on the stack and remains there until it’s countered or resolves. Spell cards are physically placed on the stack. For abilities, a pseudospell with the text of the ability goes on the stack. All other characteristics of the pseudospell depend on the characteristics of the ability’s source. For example, such a pseudospell’s color would be continuously determined by the color of its source, not just the source’s color when the pseudospell went on the stack.

409.1b If the spell or ability is modal (uses the phrase “Choose one —” or “[specified player] chooses one — “), the player announces the mode choice. If the spell or ability has a variable mana cost (indicated by “X”) or some other variable cost, the player announces the value of that variable at this time. If the spell or ability has alternative, additional, or other special costs (such as buyback or kicker costs), the player announces his or her intentions to pay any or all of those costs (see rule 409.1f).

409.1c If the spell or ability requires any targets, the player first announces how many targets he or she will choose (if the spell or ability has a variable number of targets), then announces the targets themselves. A spell or ability can’t be played unless the required number of legal targets are chosen. The same target can’t be chosen multiple times.
If the spell or ability targets one or more targets only if an alternative, additional, or special cost (such as a buyback or kicker cost) is paid for it, or if a particular mode is chosen for it, its controller chooses those targets only if he or she announced the intention to pay that cost or chose that mode. Otherwise, the spell or ability is played as though it did not have those targets.

409.1d If the spell or ability affects several targets in different ways, the player announces how it will affect each target.

409.1e If the spell or ability requires the player to divide an effect (such as damage or counters) among a variable number of targets, the player announces the division. Each of these targets must receive at least one of whatever is being divided (for example, damage or counters); this doesn’t apply when the player isn’t given a choice.

409.1f The player determines the total cost of the spell or ability. Usually this is just the mana cost (for spells) or activation cost (for abilities). Some cards list additional or alternative costs in their text, and some effects may increase or reduce the cost to pay. Costs may include paying mana, tapping cards, sacrificing permanents, discarding cards, and so on. The total cost is the mana or activation cost, plus all cost increases and minus all cost reductions. Once the total cost is determined, it becomes “locked in,” and the player then pays all costs in any order. Partial payments are not allowed. If effects would change the total cost after this time, they have no effect. If the cost includes mana, mana abilities can be played at this time. (See rule 411, “Playing Mana Abilities.”)
Example: You play Death Bomb, which costs 3B and has an additional cost of sacrificing a creature. You sacrifice Thunderscape Familiar, whose effect makes your black spells cost 1 less to play. Because a spell’s total cost is “locked in” before payments are actually made, Death Bomb costs 2B, not 3B, even though you’re sacrificing the Familiar.

409.1g Once the steps described in 409.1a–409.1f are completed, the spell or ability becomes played. Its controller gains priority.

Since you choose targets before paying the cost for an ability, you can't target the creature you intent to sacrifice.