Activate Selvala by paying ({G} magic symbol) and tapping it, adding an amount of ({G} magic symbol) equal to the greatest power among creatures you control.
Cast Wurmcalling with buyback by paying a total of at least ({5} magic symbol) ({G} magic symbol) ({G} magic symbol) .
Raggadragga's third ability triggers, giving Selvala +7/+7 until end of turn and untapping Selvala.
Resolve Wurmcalling, creating a Wurm creature token and returning Wurmcalling to your hand.