Shapeshift is a Classic depreciated predecessor advantage to Shapeshifting in 4e.
It had no assigned base cost, instead this was constructed as a Positive Point Total, with a limitation of a Negative Point Total, which operated similarly to Temporary Disadvantages in that points saved by the limitation could not exceed 80% of the NPT, so despite the -75% cap (in 3e) on limitations, more than -75 points would usually be bought to make sure that cap is reached.