Walker of Secret Ways

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever this creature deals combat damage to a player, look at that player's hand.
{1}{U}: Return target Ninja you control to its owner's hand. Activate only during your turn.

Planechase Anthology

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Walker of Secret Ways deals combat damage to a player, look at that player's hand.
{1}{U}: Return target Ninja you control to its owner's hand. Activate this ability only during your turn.

Planechase 2012

Salvat 2005

Betrayers of Kamigawa

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card into play from your hand tapped and attacking.)
Whenever Walker of Secret Ways deals combat damage to a player, look at that player's hand.
{1}{U}: Return target Ninja you control to its owner's hand. Play this ability only during your turn.