In a post-apocalyptic world, monster-like creatures have taken over most of the planet, and twenty years later, only a few clusters of humanity still remain with somewhat functioning governments, and with "towns," as in places with apartments/buildings that have barely functioning water and electricity and other necessities that people live in, that are scattered across what's left of America. These “towns” also have a pseudo-military force that both protects the citizens from the creatures, and also tries to reclaim the lost territory to these monsters, as they are not invincible, and do have a weakness.
Light. As in, any form of visible light on the electromagnetic spectrum, and also certain forms of UV light, specifically the kind produced by high electrical discharges. Now, this might seem like a weakness that should cripple these monsters, because hey, the sun should be making short work of them, but it doesn’t. Because the day these monsters started appearing was the day near-total darkness covered the world and blocked all forms of light coming from the sun, making a world that is near-pitch black. And yes, this should cause the extinction of all life, but for this question, assume that the darkness is magic and that any of the issues caused by the sun being blocked out by clouds of darkness aren’t an issue because the plants, people and planet in general adapted due to, again, magic.
So, these creatures don’t like light. Seemingly, the greater the intensity, the more it actually hurts them. Bits of their skin seems to turn into little black motes that fade into the air, seemingly burning them and causing varying degrees of pain depending on the light in question. The survivors of this world have made a list of how each type of light hurts them. Here is this list in question:
Fire seems to irritate the creatures greatly. A large campfire would make one these creatures growl and hesitate for a moment, but they would, eventually, move on, and it would cause them no real damage. A forest fire, on the other hand, would cause the creatures harm and make the creatures back off.
Flashlights seem to do some damage, burning skin on the area on which the light was shone and causing the “black mote” effect as mentioned previously, but this is more likely to anger them and cause them to attack whoever shone the light, rather than scaring them off.
Spotlights do greater damage to the creatures than flashlights, and would be enough to convince a single creature to back off if there were say, three of them being pointed in their general direction, but if the creatures were in a large group, than they would be convinced they could destroy the lights before they could do serious damage to them and attack the people shining said lights on them.
Flashbangs seem to greatly upset the creatures even more so than spotlights. Not only will it burn them, but it will also heavily disorient the creatures for several seconds. Enough exposure to the flashbangs explosions will eventually kill the creatures if they don’t get out of the blast radius. If an adequate amount of flashbangs are used, say a few dozen, than if the group isn’t large enough, say less than fifty, they will retreat. However, they are likely to return with reinforcements to try again, say anywhere between half-an-hour to an hour.
Lightning, and electrical discharges on a similar scale, seem to hurt the creatures the most. Any time lightning strikes near these creatures, even if it strikes a place hundreds of feet away, it will cause great burns to the creatures and kill them if they are close enough. The creatures in question will also tend to avoid any areas where lightning or similar electrical discharges have gone off for a few hours, as for some reason, if they enter that area within the stated time, it burns their skin. The only exception is if the creatures know there are humans in that area, as they will go back there once they gather enough forces, even if the area itself is still harmful to them.
Regular guns and ammunition do seem to damage them, but in the same way a rock would damage a gorilla. It hurts, definitely, and with enough of it could even kill them, but it’s just as likely to piss off the hulking mass of muscles as it is to kill them (Note: Not all the creatures are like this, they come in various shapes and sizes, this is just one example, but they do all share the same level of durability).
Given all of this information, and assuming that the survivors have an adequate supply of ammunition and weapons on hand that will last them a while so long as they are used reasonably, what tactics could the remnants of humanity come up with to deal with these creatures? Both in terms of protecting their “towns,” and for killing the creatures in their own territory as the humans try to regain what was once theirs.