Cast Gigantoplasm by paying ({3} magic symbol) ({U} magic symbol) , choosing to have it enter the battlefield as a copy of Wispweaver Angel.
When Gigantoplasm enters the battlefield, it triggers, blinking Wispweaver Angel.
When Wispweaver Angel enters the battlefield, it triggers, blinking Gigantoplasm, with Gigantoplasm entering the battlefield as a copy of Wispweaver Angel.