Attachments are a type of ability card in Shadow Era.

Attachments can target heroes or allies (sometimes either) on either side of the field depending of the card, "attaching" to them to give the hero or ally various extra effects. When an ability is attached to a card, it is placed behind the card it is attached.
Some attachments are positive giving your hero or allies extra health or attack, others are negative and allow you reduce the attack or health of opposing allies for example.
Attachments can be removed from their target by killing the ally, returning it to its owner's hand, or by using a card that can destroy attachments (e.g. Sever Ties).