وأما القلب فنوعان
Reversal has two forms.
In qalb the opponent uses the proponent's own proposed attribute against the proposed inference. In one form, the asserted direction of dependence between cause and ruling is reversed; in another, the very same alleged cause is made to support the opposite legal outcome.
Merely reversing a sentence is not enough. The opponent must justify why the attribute has the countervailing legal implication. Without such a link, the supposed reversal is no more than an unsupported contrary assertion.