Let's look at case law. Here are the best examples I can find covering themany and different situations you describe.
My understanding of Virginia law is that if physically confronted by multiple attackers (especially ones armed with baseball bats, sticks, etc), use of lethal force may be justified. No. See Sands and Barbosa. Your attackers being armed with baseball bats, sticks (just another name bor baseball bats) may change the situation enough to overcome the "No" answer.
Now is it different if they tell you they are only going to "detain" you , not kill you? Legally, do you have to trust them and surrender? Or can you use lethal force to avoid being unlawfully imprisoned by civilians? Maybe. See Sands, Barbosa and Payne. But then also see http://www.virginia1774.org/Dodson.html which goes into great detail not only about the differences between justifiable and excusable homicide (both of which, contrary to certain opinions, apply to private citzens as well as the police) and the various "serious" felonies for which one may use deadly force to defend oneself from or prevent being committed upon another.
Meanwhile, would you use the lethal force when they had overwhelming numbers? I know many here carry a BUG and / or extra mags, but a group of 500 could get pretty ugly... No. See Sands, Barbosa, and Payne.
Fear Alone is not Enough
Commonwealth v. Sands, 262 Va. 724, 553 S.E.2d 733 (2001).
"The principles governing a plea of self-defense are well-established. Self-defense is an affirmative defense to a charge of murder, and in making such a plea, a "defendant implicitly admits the killing was intentional and assumes the burden of introducing evidence of justification or excuse that raises a reasonable doubt in the minds of the jurors." McGhee v. Commonwealth, 219 Va. 560, 562, 248 S.E.2d 808, 810 (1978). The "bare fear" of serious bodily injury, or even death, however well- grounded, will not justify the taking of human life. Stoneman v. Commonwealth, 66 Va. (25 Gratt.) 887, 900 (1874). "There must [also] be some overt act indicative of imminent danger at the time." Vlastaris v. Commonwealth, 164 Va. 647, 652, 178 S.E. 775, 776 (1935). See also Yarborough v. Commonwealth, 217 Va. 971, 975, 234 S.E.2d 286, 290 (1977); Mercer v. Commonwealth, 150 Va. 588, 597, 142 S.E. 369, 371 (1928). In other words, a defendant "must wait till some overt act is done[,] . . . till the danger becomes imminent." Vlastaris, 164 Va. at 652, 178 S.E. at 777. In the context of a self-defense plea, "imminent danger" is defined as "[a]n immediate, real threat to one's safety . . . ." Black's Law Dictionary 399 (7th ed. 1999). "There must be . . . some act menacing present peril . . . [and] [t]he act . . . must be of such a character as to afford a reasonable ground for believing there is a design . . . to do some serious bodily harm, and imminent danger of carrying such design into immediate execution." Byrd v. Commonwealth, 89 Va. 536, 539, 16 S.E. 727, 729 (1893).
In holding that the trial court erroneously refused to instruct the jury on self-defense, the Court of Appeals construed the term "imminent" to mean something less than "immediate." Sands, 33 Va. App. at 678, 536 S.E.2d at 465 (quoting Sam v. Commonwealth, 13 Va. App. 312, 325, 411 S.E.2d 832, 839 (1991)). Applying its view of that term, the Court of Appeals concluded that, "[u]nder the facts of this case, the fact finder could reasonably have concluded that [the defendant] was without fault in beginning the altercation, reasonably apprehended she was in imminent danger of death or serious bodily harm and, thus, was justified in shooting her husband to prevent him from killing her or further inflicting serious bodily harm upon her." Sands, 33 Va. App. at 679, 536 S.E.2d at 465.
We agree that the defendant reasonably believed that she was in danger of serious bodily harm or death. Nevertheless, that reasonable belief is not dispositive of the issue before us in this appeal. The question here is whether the circumstances immediately surrounding the killing, specifically, the actions of the defendant's husband at that time, were sufficient to create a reasonable belief of an imminent danger which had to be met. The Court of Appeals did not squarely address this requirement of an overt act.
Even when viewed in the light most favorable to the defendant, the evidence fails to reveal any overt act by her husband that presented an imminent danger at the time of the shooting. The last episode between the defendant and her husband occurred after the defendant telephoned Shelton. Then, sufficient time elapsed for Shelton to arrive at the couple's home, and for the defendant to view the extent of her injuries while in the bathroom with Shelton, walk from the bathroom to the living room door, turn around and proceed back into the kitchen, retrieve a gun from a cabinet, and walk back into the bedroom where her husband was reclining on the bed, watching television. At that moment, the only reaction by the defendant's husband was his question, "What are you doing[?]" While we do not doubt the defendant's genuine fear for her life or minimize the atrocities inflicted upon her, we cannot point to any evidence of an overt act indicating imminent danger, or indeed any act at all by her husband, when she shot him five times while he reclined on the bed. Nor did the Court of Appeals cite to any such evidence. Thus, the defendant was not entitled to an instruction on self-defense. The requirement of an overt act indicative of imminent danger ensures that the most extreme recourse, the killing of another human being, will be used only in situations of necessity. "The plea of self-defense is a plea of necessity and the necessity must be shown to exist or there must be shown such reasonable apprehension of the immediate danger, by some overt act, as to amount to the creation of necessity." Vlastaris, 164 Va. at 651, 178 S.E. at 776.
"...Thus, . . . [one] who expects to be attacked should first employ the means in his power to avert the necessity of self-defence, and, until he has done this, his right of self-defence does not arise." Hash v. Commonwealth, 88 Va. 172, 192, 13 S.E. 398, 405 (1891). "The 'bare fear' of serious bodily injury, or even death, however well-grounded, will not justify the taking of human life." Commonwealth v. Sands, 262 Va. 724, 729, 553 S.E.2d 733, 736 (2001)..."CONCLUSION For these reasons, we will reverse the judgment of the Court of Appeals and enter final judgment reinstating the convictions. Reversed and final judgment."
Disparity of Force not a Defense by Itself
Andre Barbosa v. Commonwealth Va. App. (2002 Unpublished)
"...Under these facts, we hold, therefore, that it was not "necessary" for Barbosa to use deadly force to avert the perceived impending "gang beating." The fact that he was surrounded by Serna and his friends and that Serna "bumped into his gun," stating he was not afraid, does not constitute an "overt act indicative of imminent danger." See Vlastaris v. Commonwealth, 164 Va. 647, 651-52, 178 S.E. 775, 776-77 (1935) (holding that accused's fear for his life was without foundation because victim made no overt act at the time of the shooting). "
Decarlos Coleman v. Commonwealth, Va. App. (2002 Unpublished)
"Appellant next contends the trial court erred in refusing to instruct the jury on self-defense. We disagree.
"Self-defense is an affirmative defense which the accused must prove by introducing sufficient evidence to raise a reasonable doubt about his guilt." Smith v. Commonwealth, 17 Va. App. 68, 71, 435 S.E.2d 414, 416 (1993) (citing McGhee v. Commonwealth, 219 Va. 560, 562, 248 S.E.2d 808, 810 (1978); Yarborough v. Commonwealth, 217 Va. 971, 979, 234 S.E.2d 286, 292 (1977)). "[A] person assaulted while in the discharge of a lawful act, and reasonably apprehending that his assailant will do him bodily harm, has the right to repel the assault by all the force he deems necessary, and is not compelled to retreat from his assailant, but may, in turn, become the assailant, inflicting bodily wounds until his person is out of danger." Dodson v. Commonwealth, 159 Va. 976, 979, 167 S.E. 260, 260 (1933) (quoting Jackson's Case, 96 Va. 107, 30 S.E. 452 (1898))."
See Also : Gilbert v. Commonwealth, 28 Va. App. 466, 473, 506 S.E.2d 543, 546 (1998).
What Is Great or Serious Bodily Injury?
Commonwealth v. Bernard Payne, Va. App. (1996 Unpublished)
" Bernard Payne was charged with violating the felony provision of Code § 46.2-817. The trial court held that the term "serious bodily injury" was unconstitutionally vague and dismissed the felony charge. The Commonwealth appeals...
Furthermore, in determining the meaning of a statute, "[t]he validity of using other Code sections as interpretive guides is well established. The Code of Virginia constitutes a single body of law, and other sections can be looked to where the same phraseology is employed." King v. Commonwealth, 2 Va. App. 708, 710, 347 S.E.2d 530, 531 (1986). Code § 18.2-369, which concerns abuse or neglect of incapacitated adults, reads: "For purposes of this subsection, 'serious bodily injury or disease' shall include but not be limited to (i) disfigurement, (ii) a fracture, (iii) a severe burn or laceration, (iv) mutilation, (v) maiming, or (vi) life threatening internal injuries or conditions, whether or not caused by trauma." The term "serious bodily injury" can also be found in other statutes. See Code § 10.1-1455 (handling of hazardous wastes), 16.1-228 (family abuse definition), 16.1-269.1 (transfer of juveniles to circuit court), 17-237 (sentencing guidelines), 18.2-67.3 (aggravated sexual battery), 29.1-740 (duty to stop and render assistance); 54.1-2400.1 (duty of mental health service providers to prevent violence), and 54.1-3434.3 (denial, revocation, and suspension of pharmacy registration). With such widespread use of the term, it is plain that the term does have a common and well-recognized meaning. As such, ordinary people can understand what conduct is prohibited and the inclusion of the term in the statute does not encourage arbitrary and discriminatory enforcement. Therefore, the term is not unconstitutionally vague."
From deep within the decision:
[2-4] "Homicide in defense of person or property, under certain circumstances of necessity; which is justifiable by the permission of the law. This takes place when a man, in defense of his person, habitation or property, kills another, who manifestly intends and endeavors, by violence or surprise, to commit a forcible or atrocious felony upon either. In the cases to which this ground of justification applies, no felony has been committed, but only attempted; and the homicide is justifiable in order to prevent it. "All felonies may not be so prevented. A distinction is made between such felonies as are attended with force, or any extraordinary degree of atrocity, which in their nature betoken such urgent necessity as will not allow of any delay, and others of a different kind and unaccompanied by violence on the part of the felon. Those only which come within the former description may be prevented by homicide; as murder, rape, robbery, arson,  burglary and the like.
Note that kidnapping is not specifically mentioned. One would need to make the case sucessfully thast kidnapping is amond "the like" as murder, rape, robbery, arson and burglary.
As a further note, I feel it must be mentioned that subsequent case law has modified the view that robbery and burglary are crimes sufficiently of a degree of atrocity as to warrant either excusing or justifying homicide. In the words of someone great, "It just aint so no more."