Flying
At the beginning of your upkeep, put a +1/+1 counter on Phantasmal Sphere, then sacrifice Phantasmal Sphere unless you pay for each +1/+1 counter on it.
When Phantasmal Sphere leaves the battlefield, put a blue Orb creature token with flying onto the battlefield under target opponent's control. That creature's power and toughness are each equal to the number of +1/+1 counters on Phantasmal Sphere.