From DominionStrategy Wiki
A junking attack or junker is an Attack card that puts undesirable cards—i.e., "junk"—into an opponent's deck, thus weakening the average strength of their hands and usually slowing cycling. The undesirable card par excellence is the Curse, and most junking attacks are cursers.
Some cards distribute undesirable cards other than Curse (cards in italics have been removed):
- Mountebank (is also a curser), Noble Brigand and Greed distribute Copper.
- Marauder and Cultist distribute Ruins.
- Swindler, Ambassador, Masquerade, and Jester can distribute a wide variety of junk cards, depending on cards they are collided with or that are revealed from your opponent's deck.
- Locusts and Barbarian can let the victim choose what card to gain, subject to certain cost and type restrictions; if there are no desirable cards available meeting those criteria, they may be forced to gain a junk card.
- Messenger can act as a junker, depending on what you choose for everyone to gain.
- Embassy and Governor are not attacks but distribute Silver to opponents. This can often have a negative impact on deck control, but is generally less harmful than the other cards that are distributed by junking attacks.
- Shaman can put cards in the trash, and forces everyone to gain from the trash. Thus if you trash a junk card from your deck, your opponent may be forced to gain it on their next turn.
For a gallery of cursing attacks, see here.
 Other junkers
 Removed cards