An emulator allows you to play a card not in your deck—in effect, they allow you to "emulate" the effects of other cards. Many are also Commands. Emulator cards provide extra flexibility and reliability to the deck: when you draw such a card, you get to choose from the effects of whichever other cards would be the most beneficial for you on this particular turn. Because of this flexibility, most emulators restrict what you can play, such as by only playing cards from the Supply up to a certain cost. So if you need expensive cards, you'll have to buy them straight out. Emptying a Supply pile can severely weaken emulators because there's one less card they can copy.
 List of emulators
- Overlord—emulates a card in the Supply costing up to :
- Necromancer—emulates a card in the trash :
- Band of Misfits—emulates a card in the Supply costing up to :
- Captain—emulates two cards in the Supply costing up to :
- Inheritance—causes your Estates to emulate a card from the Supply costing up to :
 Tracking Rules
- Some cards can play a card that isn't put into play.
- When you play one of these cards, leave it in play as long as you would have left the card it plays in play.
- If it plays multiple Duration cards (e.g., you used Throne Room on it), leave it out until the Clean-up of the last turn that one of them still had effects.
 Rules complications with emulators
Early emulators—prior versions of Band of Misfits, Inheritance, and Overlord—acted by actually changing the identity or abilities of the emulating card. Thus when you played a Band of Misfits, for example, it "became" a copy of whatever card it was emulating until it left play, and was counted as such for the purposes of such cards as Horn of Plenty. Donald X. had expressed dissatisfaction with this state of affairs because it involved "shapeshifting": two copies of the same card in different locations (e.g., a Band of Misfits in play and one in the trash, or an Inherited Estate in your deck and one in an opponent's deck) might have different names and/or abilities. This led to the Dominion 2019 Errata and Rules Tweaks that altered these to work like the later emulators.
The later emulators (Necromancer and Captain) work in a different way: technically, instead of "becoming" the emulated card, they just cause the emulated card to be played without entering the play area (i.e., "leaving it there"). Certain of these cards are not allowed to emulate Duration cards, to avoid confusion caused by Duration cards being played with nothing left in play to track them. New tracking rules were added to allow some of these later-style emulators to track Duration cards (either playing them or playing a card that plays them multiple times).
Later emulators are more effective at playing one-shots than earlier ones: if you play an Experiment with Captain nothing returns to the Supply, whereas older versions of Band of Misfits that played an Experiment would. On the other hand, earlier emulators are more effective with cards that have a "while this is in play" ability, such as Highway, or a "when you discard this from play" ability, like Herbalist; with later emulators, the emulated card is never put into play those abilities are never triggered. For these reasons, certain one-shots were given errata to have some of their effects contingent on trashing.