Put a Naterran Great Tree token into your EX area. Combo (3) - Put 2 instead and give your leader +2.
QIf my EX area is full, can I still play this spell?
AYes. Since your EX area is full, if you play this spell, it will have no effect. However, if you've played at least 3 cards this turn, you will give your leader 2 defense.