Neera, Scion of Grace

Vigilance
As long as you control at least four creatures with flying, Neera, Scion of Grace gets +2/+1, has flying, and is an Angel.
At the beginning of your upkeep, if Neera is an Angel, you may pay {x}. If you do, search your
library for an Angel creature card with converted mana cost X or less and put it onto the
battlefield. Then shuffle your library.