Roaring Thunder

When Roaring Thunder enters the battlefield, sacrifice all dragon creatures you control. Roaring Thunder gains flying and
{x} +1/+1 counters where {x} is the total strength of every creature sacrificed this way.
If Roaring Thunder would be dealt damage, prevent that damage and remove 2 +1/+1 counters from it, then create a 1/1 red dragon creature tokens with flying.