1Activate Spark Double using Avatar Kuruk's ability by paying minus for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
2Activate Fortune's saddle ability by tapping Spark Double, causing Fortune to become saddled until end of turn.
3Declare Fortune as an attacker. At end of combat, Fortune triggers, blinking it and Spark Double. Choose to have Spark Double enter the battlefield as a copy of Avatar Kuruk.