Inversion

Subject-operator inversion after most initial negative / restrictive elements has a rhetorical effect and is virtually restricted to writing. However, after initial "nor" or "neither" this inversion is found in conversation as well as writing.
Subject-operator inversion can also be found after opening elements consisting of the degree adverb "so" followed by an adjective or adverb; similarly after clause-initial "such":
E.g. So absurd did his story sound that at first nobody believed him.
So great was our surprise that we were utterly speechless.
So greatly had he suffered that death came as a relief.
Such self-confidence did he feel that he ignored all our warnings.
This type of inversion can also be found in subordinate clauses of hypothetical condition, especially in rather formal usage:
Were we to withdraw our support, the enemy would defeat them within two weeks. (= If we were ...)
Subject-verb inversion
Subject-verb inversion is normally limited as follows:
• The clause opens with an adverbial, especially one of place or direction. This adverbial often links the clause explicitly to the preceding text. The opening element may also be a subject complement linked to the preceding text.
• The verb phrase consists of a single verb, in the past or present tense.
• The verb is an intransitive verb of position (e.g. stand, lie) or of motion (e.g. come, go, fall). It may also be a copular verb (be).
• The verb has less weight than the subject which, through subject-verb inversion, is usually given end-focus.
• In informal speech, subject-verb inversion generally occurs only after "here" and "there".