Depending on the nature of the case (e.g., medical malpractice, trust/will challenges for lack of capacity or undue influence, etc.), medical testimony is often crucial. The qualification of a physician as an expert is generally within the trial court’s substantial discretion. Ponciroli v. Wyrick, 573 S.W.2d 731, 735 (Mo.Ct.App.1978). Generally, a practicing physician, even when…