Kelvin Helmholtz

When Kelvin Helmholtz enters the battlefield,
you may sacrifice any number of Clouds you
control. If you do, put that many +1/+1 counters
onto Kelvin Helmholtz and add that much
{w} and/ or {u}.
{1}{w}{u}: Evapourate 1 (Create a 1/1 Cloud creature
token with flying.)