Arwen, Seer of Umbra Forest

Ethereal (This creature can only block or be blocked
by creatures with flying and spirit creatures.)
At the beginning of your upkeep, if you control
three or more creatures, scry three. Otherwise,
exile cards from the top of your library until you
exile a nonland permanent card that shares a
color with this permanent. Put that card onto
the battlefield tapped.

There is strength in numbers.