I'd like to see a hat that gives a button to turn into a statue for a second and receive 0 damage. A stone mask or something. And for an example of what I mean: the raccoon suit from Super Mario 3. My only concern would be the freeze, since you use it standing still. Or, the option could be long statue time with high freeze coming out of the mode.
And, it shouldn't be used to block doors, since that would be an abuse. For that reason a small time would be better with a semi-long "reload" wait.