Mist Raven

Flying
When Mist Raven enters, return target creature to its owner's hand.

Unsummon

Return target creature to its owner's hand.

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When Breaching Hippocamp enters, untap another target creature you control.

Wind Drake

Storm Crow

Flying (This creature can't be blocked except by creatures with flying or reach.)

Augury Owl

Flying
When Augury Owl enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Counterspell

Sage of Epityr

When Sage of Epityr enters, look at the top four cards of your library, then put them back in any order.