Does equip's activated ability use the stack and can your opponent respond to it?

Equip is an activated ability with the cost written as 'Equip [cost]' and found on Equipment cards. Like all activated abilities, it is placed on the stack when activated and can be responded to by any player with priority before it resolves. This is governed by CR 602.2, which explains how activating an ability works, and CR 112.3a, which confirms activated abilities use the stack.

Because the ability uses the stack, your opponent has a window to respond after you pay the equip cost and announce the ability. They can cast instants, activate abilities, or even destroy the target creature before the Equipment attaches. If the creature the Equipment was targeting is no longer a legal target when the ability tries to resolve, the ability is countered and the Equipment stays where it was (CR 608.2b).

Similarly, opponents can also destroy the Equipment itself in response. However, destroying the Equipment does not automatically stop the ability already on the stack — the ability and the Equipment card are separate objects once the ability is on the stack (CR 112.7a). But since the Equipment is gone, even if the ability somehow resolved, there would be no Equipment to attach, so it would simply fail to do anything meaningful.

Concrete example: You activate your Bonesplitter's Equip ability targeting your 2/2 creature, paying {1}. Your opponent responds by casting Lightning Bolt targeting that 2/2. The creature dies before Equip resolves, so the Equip ability is countered on resolution due to an illegal target, and Bonesplitter remains unattached.

The key practical lesson: equipping is not instant-speed protection. Always equip during your second main phase or when your creature is reasonably safe, since the window for opponents to respond is very real.