Equip Spell Card

Equip Spell Card
An Equip Spell Card is a Spell Card that is equipped to a face-up Monster on the Field.

When you activate an Equip Spell Card, you must target a face-up Monster on the Field to equip the Card to; the Equip Spell Card's effect applies to that Monster as long as it is equipped. Equip Cards constantly target the Monster they are equipped to; even while negated, Equip Cards remain equipped and continue to target the Monster. If the equipped Monster is no longer face-up on the Field or is no longer a valid target, then the Equip Card is immediately destroyed.

Control does not matter
Equip Cards can be equipped to Monsters controlled by either player, and changing control of a Monster does not cause control of an Equip Card to change. While the equipped Monster can be the opponent's, the Equip Card's controller is the one referred to as "you" in the Equip Card's Card text, not the controller of the equipped Monster.

An ATK-boosting Equip Spell Card is "Axe of Despair".
A DEF-boosting Equip Spell Card is "Horn of Light".
Some Equip Spell Cards with unusual effects are "Premature Burial" and "Amplifier".
Some Equip Spell Cards have a negative effect like "Mask of Brutality" and "Darkworld Shackles".