How do i make a touch function that hits multiple people, but only once?

Im making an aura attack move, but its only able to attack 1 person at a time. Here is my script

Strong.Touched:connect(function(hit)

if not debounce then return end
debounce = false
local dmg = math.floor(script.Parent:FindFirstChild("Charging").Value / 1.55 + baseAtk + 1)
local opponent = hit.Parent:findFirstChild("Humanoid") or hit.Parent.Parent:findFirstChild("Humanoid")
		if opponent and opponent ~= player.Character.Humanoid then
		   opponent:TakeDamage(dmg)

wait(0.23)
debounce = true	
end)

Your usage of a debounce variable is stopping it from running on more than one player at a time. Since, I assume, you have the debounce there to stop it from damaging the same player more than once, you should use a table for that instead:

local debounceTab = {};
Strong.Touched:Connect(function(hit)
	local opponent = hit.Parent:FindFirstChild("Humanoid") or hit.Parent.Parent:FindFirstChild("Humanoid");
	if opponent and opponent ~= player.Character.Humanoid then
		if debounceTab[opponent] then return end;
		debounceTab[opponent] = true;
		local dmg = math.floor(script.Parent:FindFirstChild("Charging").Value / 1.55 + baseAtk + 1)
		opponent:TakeDamage(dmg)
		wait(0.23)
		debounceTab[opponent] = nil;
	end
end)

Also, I noticed you had an end missing in your code. I'm not sure how it didn't error. Make sure you correctly indent your code!
Hope this helped.