Was used(I think )only twice:Once,in the black and white first season Halloween episode with Dick York as Darrin "The Witches Are Out",by Bertha(Madge Blake),and later on in a color episode with Dick Sargent as Darrin,when Maurice taught it to him.Was this chant used on any other episodes?Or were those the only two times?

Probably

As far as I can remember.