BEFORE tweening, create a two, three or more distorted ovals without outline, on seperate layers, overlapping as required for depth of mist, the more layers with high transparancy the better, fill with and modify one of the gradiated fills provided, then use 'Modify', 'Curves', 'Soften Edges, If you want to move each individual mist cloud, then lock the others first, then 'Select all', otherwise you will only move a section of the gradiated mist, THEN tween all layers, stagger all tween's with alpha changes, scale and rotation, interdispersed in each layer, delicate changes work best....good luck