Does Siphoned Power affect only units currently at the chosen battlefield when it resolves, or does it create a continuous effect that affects units that move there later in the turn?

Ruling: Siphoned Power only affects units that are at the chosen battlefield when the spell resolves. It does not create a continuous effect on the battlefield that would affect units arriving later.

Sequence:

• When Siphoned Power resolves, choose a battlefield
• All friendly units currently at that battlefield gain +1 Might for this turn
• All enemy units currently at that battlefield lose -1 Might (minimum 1) for this turn
• Units that move to that battlefield later in the turn are not affected
• Units that were affected and then leave the battlefield retain the buff/debuff for the duration

Nuances:

• The phrase "give" indicates a one-time effect that snapshots which units are present, not a continuous passive ability
• If the card were meant to create a continuous effect on the battlefield, it would be templated differently (e.g., "Until end of turn, friendly units there have +1 Might")
• The "for this turn" text refers to the duration of the Might change given to the current units, not an aura on the battlefield itself
• This is a common misreading of the card where players think the battlefield gets an aura effect