How do normal-sized creatures acutally kill giants and other big monsters with melee weapons?

[Yqatuba]

If the giant is only like 12 feet tall I could see stabbing it in the femoral artery or something, but what about, say, Mogaru? A human would only come up to like his ankle joint. How could hitting him there kill him?

[DeathlessOne]

You mean realistically? Because the game just has you eliminate the HP of the target to defeat it (usually). It a rough simulation of wearing the opponent down, striking it in spots that are open when it tries to hit you (bringing limbs into easier reach), until it is in a position in which you can strike to fatal blow.

And a Mogaru is a Kaiju. You don't use conventional physics or battlefield tactics to kill those things. You use weapons and abilities that are far from 'normal', like magic. You need equally powerful beings to fight such things. A typical human near the ankles of such a thing is going to get trampled. It has DR/epic and fast healing 30. A normal human isn't going to do anything to it.

[VoodistMonk]

Ever seen that Chucky movie where he hides under the bed and cuts that dude's achilles tendon?

Assuming they have similar anatomy, you would target the spots that are vital to balance and movement within reach. The idea would be to hamper their movement enough that you could slowly pick away at their health to bleed them out. Think of wolves taking down a moose... nip its heels until it stumbles, then grab its nose or throat.

In PF1, though, you just roll to see if your attack beats their AC, then subtract your damage from their HP... a giant with 100% HP and a giant with 1% HP fight and move the exact same... there really is no cutting its achilles tendon in PF1, even though that is traditionally how small things kill bigger things...

[Mark Hoover 330]

Aren't there anime movies out there where an unarmored sword wielder deals a single attack that, at first, doesn't seem to have done anything but seconds later a 15' tall demon-tainted villain splits in half in a fountain of gore? Like, Attack on Titan, Ninja Scroll, and so on? Why can't the attack just look like these?

I mean, this is a game where it's entirely conceivable that a 16th level fighter with a 2-handed weapon deals 120 damage in 6 seconds. Do you understand just how much damage that is? That's nearly enough to get through a solid tree 1' around. In 6 seconds. Another way to look at it, with Whirlwind Attack and dealing an average of 30 damage per hit, that fighter can stand at the center of a pack of 8 dire hyenas, Large sized creatures, and conceivably drop all of them to Dying in SIX SECONDS with the right feats.

This is not a game based in reality. This is a game where flying reptilian creatures the size of a house breathe lightning or fire enough slay a small platoon. This is a game where spellcasters can make the ground open up and create a massive pit filled with spikes and acid. A single strong PC, with enough skill backed by pure rage, can slam the ground and cause it to buckle into Difficult Terrain. Physics and biology rules waved bye bye to this game a long time ago.

[Phoebus Alexandros]

A normal human stabbing with its spear at a Cloud Giant’s leg might be described as barely scratching its shiny or thigh, if he even penetrates its inches-thick sculpted leather greaves. Player Characters, however, get into melee combat with Giants tend to do so after having procured some degree of magic, generally speaking. They wield enchanted weapons, belts that enhance their physical prowess, and so on. In fewer words, they are able to deal effectively superhuman amounts of damage. So maybe that 11th level Fighter is only reaching the Cloud Giant’s knee, but he can hit it hard enough to make him buckle.

The rules don’t provide a complete simulation, of course. Hit Points are an abstraction. The game relies on a Gamemaster to provide detail, fill in the blanks, and in general paint the scene for the players. And so the GM might describe that as the Fighter deals more and more damage, the Cloud Giant is forced to drop to a knee—which in turn allows the Fighter to start targeting his vitals, his head, and so on.

Some players are fine with that arrangement. Others, myself included, like combining detailed storytelling with optional rules like Called Shots (from Ultimate Combat) and Wound Thresholds (from Pathfinder Unchained). The latter of those could probably benefit from movement penalties to at the Wounded and Critical levels, to make it even grittier.

[Senko]

As I believe Terry Pratchett once said. When your head comes up to his waist your helmets in line with his groin and few men can take a blow there and be unaffected. Like others said most people are either bringing powerful magic and magic items to play when facing these foes or your whittling it down by targetting the vital spots within your reach.

Its been a minor gripe of mine the shift in 3rd ed with the commoners having so many NPC class levels. They may be less effective but it makes it a bit harder to show a threat slaughtering them like they really should. I think even the weakest giant is the basic frost at CR 9 which means even a solitary one is going to destroy most small villages easily as people just can't fight something like that. This is no class levels, no special skills just the innate strength and size.