If I move a unit with Stealthy Pursuer to a battlefield my opponent controls, do both Mask of Foresight and Stealthy Pursuer trigger?

Ruling: Stealthy Pursuer triggers but Mask of Foresight does not. The move trigger from Stealthy Pursuer is added to the chain during cleanup, which prevents combat from beginning until it resolves. When the trigger resolves and moves the second unit to the battlefield, neither unit is attacking alone, so Mask of Foresight's condition is not met.

Sequence:

• Unit moves to opponent's battlefield, completing the move
• Cleanup occurs, and Stealthy Pursuer's move trigger is added as a pending item on the chain
• Combat is staged but cannot begin because there is an item on the chain
• The Stealthy Pursuer trigger resolves, moving a second unit to the battlefield
• Chain empties and another cleanup occurs
• Combat begins with two units present, so Mask of Foresight does not trigger

Nuances:

• Since Stealthy Pursuer has a 'May' clause, you could choose not to resolve the move, allowing combat to begin with only one unit and triggering Mask of Foresight's bonus