Actually, the law says you can threaten to use deadly force in response to force - not just deadly force - threatening to use deadly force (ie drawing your heater and pointing it at a goblin) is only considered the use of force. This is fresh in my mind since I have to argue it on other forums at least once a month, whenever someone announces that you can't "brandish" a firearm in Texas under any circumstances.Great question illustrating an interesting problem. You are only justified in threatening to use deadly force only if you are justified in using deadly force.
Sec. 9.04. THREATS AS JUSTIFIABLE FORCE.
The threat of force is justified when the use of force is justified by this chapter. For purposes of this section, a threat to cause death or serious bodily injury by the production of a weapon or otherwise, as long as the actor’s purpose is limited to creating an apprehension that he will use deadly force if necessary, does not constitute the use of deadly force.