Sage, Datamind

Sage, Datamind enters under the control of an
opponent of your choice.
As long as Sage isn't controlled by its owner, its
controller plays with the top card of their library
revealed.

{2}{u}{u}: Counter target spell Sage's controller
controls. Sage's owner gains control of Sage and
draws a card. Only Sage's owner may activate this
ability and only if they don't control Sage.