Heart-Piercer Bow

Text:

Whenever equipped creature attacks, Heart-Piercer Bow deals 1 damage to target creature defending player controls.
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Rulings:

• 7/12/2019 Heart-Piercer Bow (not the equipped creature) is the source of the triggered ability and the source of the damage. This means that a creature with protection from green may be targeted even if Heart-Piercer Bow is equipped to a green creature, but a creature with protection from artifacts may not.
• 7/12/2019 If a creature is attacking a planeswalker, the controller of that planeswalker is the defending player.