Harness

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Harness
Keyword Action
Introduced	Through the Omenpaths 1
Last used	Marvel's Spider-Man
Reminder Text	Harness [card name] (Once harnessed, its ability is active.)
Scryfall Statistics
cards

Harness is a keyword action introduced in Marvel's Spider-Man and its associated Universes Within set Through the Omenpaths 1. It is unique to the set's Infinity Stone and its corresponding Terminus Stone, but is expected to be used in future Marvel sets, as well.

Description

Each Infinity Stone has a pair of linked abilities. The first of the two allows its controller to harness the stone, giving it the "harnessed" designation. The second is the stone's ability, which can only be used or becomes active while the card has its "harnessed" designation.

Infinity ability

Once the harnessed designation has been achieved, the card's (infinity) ability becomes active for the rest of the game.

The Universes Within refer to this ability as the ability as Origin instead. However, this is currently not covered by the Comprehensive Rules.

Rules

From the glossary of the Comprehensive Rules (September 19, 2025—Marvel's Spider-Man)

Harness

A keyword action that grants a permanent the harnessed designation. See rule 701.64, “Harness.”

From the Comprehensive Rules (September 19, 2025—Marvel's Spider-Man)

• 701.64. Harness
  • 701.64a “Harness [this permanent]” means “If this permanent isn’t harnessed, it becomes harnessed.”
  • 701.64b Harnessed is a designation that has no rules meaning other than to act as a marker that other spells and abilities can identify. Only permanents can be or become harnessed. Once a permanent becomes harnessed, it stays harnessed until it leaves the battlefield. Harnessed is neither an ability nor part of the permanent’s copiable values.

Harnessed

"Harnessed" is a designation that permanents can have. Infinity permanents have their abilities as long as they are harnessed.

From the glossary of the Comprehensive Rules (September 19, 2025—Marvel's Spider-Man)

Harnessed

A designation permanents can have. Infinity permanents have their ∞ abilities as long as they are harnessed. See rule 701.64, “Harness,” and rule 702.186, “∞ (Infinity).”

From the glossary of the Comprehensive Rules (September 19, 2025—Marvel's Spider-Man)

Infinity

1. An artifact subtype.

2. ∞ is a keyword found on Infinity cards that grants an ability as long as that permanent is harnessed. See rule 702.186, “∞ (Infinity),” and rule 701.64, “Harness.”

From the Comprehensive Rules (September 19, 2025—Marvel's Spider-Man)

• 702.186. ∞ (Infinity)
  • 702.186a ∞ (the mathematical symbol for infinity) is a keyword found on Infinity cards. “∞” is followed by ability text. Together, they represent a static ability.
  • 702.186b “∞ — [Ability]” means “As long as this permanent is harnessed, it has [ability].” See rule 701.64, “Harness.”

Rulings

• "Harnessed" is a designation that the permanent has once an ability instructs you to harness it. It has no special rules meaning other than being a designation that the ∞ ability (and, theoretically, other effects) can see.
• Until it is harnessed, The Soul Stone doesn't have the ability listed after the infinity symbol. It also doesn't have that ability in zones other than the battlefield.
• Being harnessed isn't copiable. If something else becomes a copy of The Soul Stone, it must be harnessed separately. Similarly, if The Soul Stone is already harnessed and becomes a copy of something else, it stays harnessed, though it's very likely that won't be relevant until that copy effect ends.

Examples

Example 1

The Soul Stone
Legendary Artifact — Infinity Stone
Indestructible
: Add .
, , Exile a creature you control: Harness The Soul Stone. (Once harnessed, its ability is active.)
— At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.

Example 2

The Terminus of Return
Legendary Artifact — Terminus Stone
Indestructible
: Add .
, , Exile a creature you control: Harness The Terminus of Return. (Once harnessed, its origin ability is active.)
Origin — At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.