Can you equip a Gear card during your opponent's turn?

Question

Accepted Answer

No. You may only activate a Gear card's Equip ability during that Gear controller's Main Phase while the game is in an Open State; you cannot Equip during your opponent's turn unless an effect specifically attaches the Equipment as part of that effect.

You cannot activate an Equipment's Equip ability during your opponent's turn because Gear activated abilities may only be executed during the controlling player's Main Phase during an Open State and not during a Showdown [150.2]. Attachments that happen as part of other effects (for example, a Weaponmaster play effect) are separate and can attach Equipment according to those effects' timing, not by activating Equip on the opponent's turn [821.1.b].

Check whose Main Phase it currently is. Gear activated abilities (including Equip) may only be executed during the Gear controller's Main Phase [150.2]. Confirm the game is in an Open State and not in a Showdown. Gear activated abilities cannot be executed during a Showdown [150.2]. If it is your Main Phase and the state is Open, you may activate the Equip ability by paying its costs. Paying the Equip cost attaches the Equipment to the chosen unit and causes that unit to be considered Equipped by the Gear [818.1.b] [818.2]. If it is your opponent's Main Phase, you cannot activate your Gear's Equip ability then. The only way an Equipment becomes attached outside of those timing restrictions is via another effect that explicitly attaches it (for example, a Weaponmaster Play Effect) [821.1.b].

Weaponmaster and similar play effects can attach Equipment as part of those effects and are governed by their own timing (for example, Weaponmaster triggers when you play a unit and lets you attach Equipment regardless of the usual timing of Equip) [821.1.b]. Spells or abilities that include 'attach an Equipment' in their effect (for example, Relentless Pursuit's option to attach an Equipment) attach the Equipment as part of that spell or effect; such attachments follow the timing rules for that spell or effect rather than the normal Gear Activated Ability timing [818.1.c.2] [821.1.b].

Equip is an Activated Ability that is normally printed on Gear with the Equipment tag and is formatted as a cost that, when paid, Attaches the Equipment to a chosen unit ([818.1.a] [818.1.b] [818.1.c.2]). Rule 150.2 explicitly restricts when Gear activated abilities may be executed: they may only be executed at any time during the controlling player's Main Phase during an Open State, and not during a Showdown [150.2]. Therefore, you cannot activate an Equipment's Equip ability during your opponent's turn because it is not your Main Phase in that situation. The only time an Equipment would become attached outside of activating its Equip ability on your Main Phase is when another effect explicitly attaches it (for example, Weaponmaster's Play Effect chooses an Equipment you control and attaches it to a unit as part of playing that unit, operating by its own timing rules) [821.1.b]. Examples from the provided cards: you cannot activate Hextech Gauntlets's Equip during your opponent's turn, but playing Lucian - Merciless and using Weaponmaster can attach Equipment as part of that play effect as governed by Weaponmaster's rules [821.1.b].