BEFALL', verb transitive preterit tense befell; part. befallen.
To happen to; to occur to; as, let me know the worst that can befall me. It usually denotes ill. It is generally transitive in form, but there seems to be an ellipsis of to, and to sometimes follows it.
BEFALL', verb intransitive To happen; to come to pass.
To befall of is not legitimate.