Banshee, Sonar Thief

Flying, trample
Banshee, Sonar Thief enters the battlefield
with a shield counter on it.
You may look at the top card of your library
at any time.
You may cast spells from the top of your library
by removing a counter from a creature you
control in addition to paying their other costs.
"No one puts Banshee in a corner, Tenno.
The element of surprise is in her favor."
-Lotus