DARK SOULS II

Note beforehand: Do NOT use the item called Soul of a Giant, keep them in your inventory at all times!

A completely optional boss in the Undead Crypt, immediately accessible after you defeat Velstadt, the Royal Aegis. He's a docile giant of a man who only gets aggressive if you either attack him or wander too close to him while you fetch the King's Ring that you need to progress the story.

His attacks are;
Horizontal Slash(es) - He'll do a swipe in a 180 degree arc in front of him, mostly twice and sometimes even three times. Easiest way to avoid this is either by running immediately behind him where you're entirely safe or by backing off until he's done. He often does this attack after jumping backwards, so sprint right at him and stand behind him to elude it and be able to get 2-3 swings in. Blocking it isn't advised, it's pretty much a guarantee for him to do the third sweep that way and depending on your shield, the second or third will chop half your health away.
Vertical Slash(es) - Most common attack, he raises his sword overhead and bashes the ground with it, often twice in a row. Easiest attack to outmaneuver, simple strafe right and the moment he does the second smash, get two hits in.
Leaping Smash - A caster/rangers most frequent worry, he'll attempt to regain the close quarters battle advantage by leaping at you and burying his sword into the ground at your location, simply sprint left or right or if you're a gutsy melee kind of guy, straight at him. Long recovery time so get your series of hits in right after.
Curse Orb - Rather rare attack he only really uses if you bait the distance too often, otherwise he'll barely if not never use it. It has a big giveaway as his hand glows bright red and send a red orb your way that curses you and takes away a massive amount of your health.

Word of advice, don't attack him as of yet. You could, but let me just warn you right now, his defenses will be 32 times higher than they normally would be. Most weapons/magics will do anywhere between 3 and 25 damage a hit on him and he has 8500HP so you will more than likely be fighting him for close to 30 minutes. The only weakness he has is bleed but even then you're still looking at a 18-20 minute fight.

Just progress on and retrieve the Souls of a Giant, each weakens him significantly up to the point him being even weaker than most bosses. So to get the souls, get a decent bow and a truckload of poison arrows along with elemental variety arrows. If all else fails, use your poison knives if you ever managed to find a few as drops.

Soul of a Giant #1:
Cleverly hidden in a subterranean section of the Black Gulch. Near the second (semi-hidden) bonfire you can vaguely see a small ledge off the edge poking out of the darkness, close to the set of pools with the hand-like entities and the giant worms. Drop down to the first ledge, this one has a yet-locked door leading to Darkdiver Grandahl. Facing the door, gently and slowly walk off the edge to the right and you'll land on a piece of rock that almost seems unfit to stand on. Walk off the left side this time and you'll be at the cave entrance.

Depending on if you brought help, you'll face two Giants(3 if you got one summon, 4 if you brought two). The cave is pitch black and it's strongly advised to cheat these two by shooting one of them with arrows/poison arrows and backing off where you came from, once you reach the cave exit where you landed, the giant will begin backing away until you get close again or do sufficient damage to lure him back, he'll never go past the approach to the cave exit so consider it your safety zone. Melee combat is often suicidal, it can be done but for the sake of your sanity don't. Once the last of the giants dies, you'll get a key and the soul, ride the elevator out after grabbing the chest and goodies.

Soul of a Giant #2, 3 & 4:
Gotten from the story progression as you go through the Memories of Orro, Vammar and Jeigh with the Ashen Mist Heart. These three are practically unavoidable so not much explanation is needed, you go through three different "memories" of past events, riddled with considerably tough enemies but the toughest part of all is the tight time limit. At the end of both Orro's and Vammar's you'll find a corpse of a giant entity with the soul. Jeigh's trickier cause you have to defeat a Giant boss under the same time limit, once that's done you'll find the last corpse behind it.

Soul of a Giant #5:
Drops from the Ancient Dragon at the Dragon's Nest, the very same one who gave you the Ashen Mist Heart. He's one of the toughest bosses if not the toughest boss you'll face, he's definitely a boss you can defeat but one mistake and you will be dead. There's many strategies to defeat him, mine was to bait his leg stomp or his airborne fire breath and running towards the left of his tail, striking him once or twice when he lands and repeating that. YouTube is filled with handy videos, too many for me to suggest any of them. It really comes down to being lightweight and exploiting his weakness to lightning.

You don't need the fifth Soul, though. I did it twice with four and his defenses resemble that of a late game boss with higher-than-normal defenses(4 souls puts his defense multiplier at only x2), but hey we're all completionists here so why not, right?

After Vendrick dies you'll get the Trophy, but you might have noticed there's no loot. It's in a hidden chamber close to the second bonfire in the Shrine of Amana. Spot the sole pillar in the distance and look at the ground, you'll see a vague straight path leading to it. Break the vines and pop a Human Effigy if you're not human, head inside the door and his Soul will be on a very kingly looking chair. Continue further into the cave to find his entire armor set.