Szeth, Truthless of Shinovar

Invest {1}: Szeth, Truthless of Shinovar gains
flying and becomes invested.
{t}: Szeth, Truthless of Shinovar gains
a +1/+1 counter.
When Szeth, Truthless of Shinovar leaves the battlefield while invested, you may exile it
and search your library for a card named Nightblood, Curse Sword and remove it from the
game. If you do so, return this card to the battlefield and transform it.