Cast Sakashima the Impostor by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , choosing to have it enter the battlefield as a copy of Wispweaver Angel.
When Sakashima the Impostor enters the battlefield, it triggers, blinking Wispweaver Angel.
When Wispweaver Angel enters the battlefield, it triggers, blinking Sakashima the Impostor, with Sakashima the Impostor entering the battlefield as a copy of Wispweaver Angel.