Does Wielder of Water gain +2 attack when attacking on an open battlefield (with no defending units)?

Ruling: No, Wielder of Water does not gain +2 attack when attacking on an open battlefield. A unit must be in combat to have the attacker or defender designation, and combat only opens when units controlled by different players are present on a battlefield.

Nuances:

• The attacker/defender designations require units from different players to be present on the battlefield together