Stardust Summoner

When Stardust Summoner enters the battlefield create a 5/5 Blue Stardust Guardian with "This creature can't attack" and "If you don't control Stardust Summoner sacrifice This creature at the beginning of your next end step".

Whenever Stardust Summoner leaves the battlefield create a */* blue Stardust Dragon token with flying and "Stardust dragon power and toughness is equal to your devotion to blue.