flying
at the beginning of your upkeep, put a +1/+1 counter on phantasmal sphere, then sacrifice phantasmal sphere unless you pay 1 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.