I organized the achievements in different categories to make it easier to read. All of the achievements are pretty much self explanatory. There are some that I have no idea how to get so any help would be appreciated.

There are 2 ways to get the achievements:

1) The first is to do it legitimately, this will take you a very long time to complete.

2) The second is to use tqdefiler, a character editor that will allow you to unlock all difficulties right from the start, level up your character, give you attribute points etc. It takes all the fun out of the game but if you want to get these achievements faster you may want to consider it.

Most of these are story related and can not be missed unless otherwise stated. PLEASE NOTE: If you play multiplayer you can miss out on some of these if you join a game and the host has already completed the mission. You can also replay any act to kill any optional bosses that you may have missed in epic or legendary difficulty.

Save Helos

Pass the Spartans' test

Defeat Polyphemus

Defeat the Gorgons

Defeat the Minotaur Lord

Find and defeat Talos – Only appears in Epic and Legendary at Knossos palace

Find and defeat the Boar Snatcher

Credit to Steam User Stap
Boar Snatcher - a giant spider in a cave in Spartan Woods, below the village between Sparta and Megara. Availiable on Epic and Legendary.

Find and defeat the Hydra -encounter only on Legendary Difficulty, in the Athens Marsh

Cleanse the library

Defeat the Honor Guard

Defeat Nehebkau

Find and defeat the Sandwing queen
Credit to steam user Stap:
Sandwing Queen - a giant Hag in the Sobek Plateu. Go to the Memphis and then to the Gate of the Palm, then up. Availiable on Normal, Epic and Legendary.

Defeat Aktaios

Find and defeat the Manticore-The Manticore is a very powerful boss that only appears on epic and legendary. You encounter it in the Sandswept Cave on the east of the Fayum Desert.

Credit to Steam User Stap:
Open the Pharaohs tomb in Giza 3 times (on Normal, Epic and Legendary);
Some confusion with this one.
This sidequest is related to Khufu's curse. There will be a man stadning in front on the pyramid in the desert. Open all three tombs in the pyramid. I'm not sure if the achievement is tied to opening the wrong tombs or if its related to completing the quest 3 time on each difficulty.

Defeat the Chimera

Defeat Barmanu

Defend the Great Wall

Meet the Yellow Emperor

Find and defeat the Dragon Lich -He is encountered shortly after Chang'an, at the Shrine of Zhong Kui, but only on Epic and Legendary difficulties

Credit to Steam User Stap and patlenegg
You need one of your pets to attack the telkin before you go down otherwise the telkine teleports the sickle elsewhere. After you defeat the last boss in Act 3 equip the sickle of Kronos.

Slay a titan

Find Medea

Defeat the Graeae

Cross the Styx

Walk the fields of Elysion

Finish the main storyline

Loot Hades' treasure vault – Side quest in Act 5.

First you have to find 4 stones located throughout the entire act.

Frost Stone: Carried by Thyia of the Stygian Frosts inside the Daemon camp
Flame Stone: Carried by Metriche at the Fields of the Diadochi
Soul Stone: Carried by the Night's Mistress inside the Royal Chambers
Venom Stone: Carried by Canace the Serpent Queen inside the Tower of Judgment

After you have all the stones go back to the Plains of Judgement portal, go back outside, follow the short path and enter the first cave you see. Place the 4 stones on each of the pedestals and the door should open.

Credit to VyleKillius

Upon defeating Hades, there's an 8 - 10% chance he'll drop a seemingly random quest item called The Overlord.

Where do you use it? It's small, cute, but most importantly, it opens a secret passage North East of Rhodes, in the Coastal Asomata region, which will in turn unlock the "Turtle Power" achievement:

Credit: FaithCZ
50 shades is simple, just release at least 50 souls in Hades realm in Act 5

Release 500 souls in Hades realm in Act 5

Any achievements related to masteries.

Hunter

Puncture four enemies with one arrow

Max out the skill Puncture Shot Arrow, get a group of enemies together and start shooting and hope for the best. Shouldn't be too difficult

From Steam User figmentPez [Halforums]
Found out yesterday that the Good Point achievement can be done with the Ice Shard & Velocity skill from Storm mastery. The ice shards apparently count as arrows.

From Steam User: Code: Neko
For Good point achievement, it can be done as assassin (Warfare/rogue) i was dual wielding thrown weapons, one being hanoi(the one that gives volley) and got it like that , didnt know it was possible like that so sharing something new thatd help

Keep an enemy ensnared for 30 seconds

Put a point in ensnare and keep casting it on the same enemy. Pick an enemy that has a lot of health.


Defense

Beat Polyphemus while in Colossus Form

Beat the giant troll in Act 1 in Colossus Form. May be possible in normal difficutly but I don't believe it is as you won't have enough skill points. Can be done on Epic difficulty.

Cast Rally on yourself and 3 other players

Stun an enemy for 10 seconds in one hit
Credit to Steam user Eddetektor:

Conquror(Warrior/Defense) can do it. War Horn (7,5s stun at max lv) and Consussive Blow (+65% stun at max lv) can make 12,375 s stun.
If that doesn't work, use concussive blow, use a regular club and insert relics that increase stun duration i.e Embodiment of Dionysus' Wineskin, Embodiment of Shen-Nong's Dark Medicine. Start hitting enemies and hope for the best.



Warrior

Have two Battle Standards up at the same time

In order to do this, you need to lower your casting recharge time either through equipment or using the skill in the nature mastery.

Storm

Burn an enemy's mana for 2500 damage

The only skill related to this that I could find is spell breaker/spell shook.


Earth

Defeat ten enemies over the course of one Stoneform spell

Max out Stoneform/Molten Rock, get as much elemental damage as you can get. Easier to do this in normal mode.

Rogue

Hit an enemy for 100.000 damage

The only skill that I think is suitable is Lethal Strike. If anybody else has any suggestions that would be great.

Have 10 enemies running around confused

Max out Mandrake, try to keep your damage output low so enemies don't die out on you.

From Steam User: Kulcsos12
Easiest way to get the Delirium achievement with the Rouge if you use the maxed out Flash Powder skill. Just collect 10 or more melee enemies on you and cast the skill.

Nature

Heal other players for a total of 200 000 health

Max out Regrowth skill and cast it on other people. Rally from the defense mastery will also work. Must be used on other players, your own pets will not count.

Travel with three Wolves and a Nymph

Max out Call of the Wild, then you need to either find a Mastery Shrine, or have items that boost your skills an additional +2 in order to summon 3 wolves. Putting one point Sylvan Nympth is enough.

Have 14 enemies afflicted by Plague at once

Max out Plague and get a large group of enemies togehter. Requries luck.


Spirit

Mind control six enemies at the same time

Max out Enslaved Spirit and you need to lower your casting recharge time through equipment. The max you can lower it is 80% (cap). I got this just outside of the first camp in act1 normal. It may be a bit tricky, it requires you to cast enslave spirit as soon as its recharged in order to get 6 enemies. Certain equipment also has a chance of mind control but the chances of finding them and have 6 at the same time through equipment is very minimal.

Summon a level 20 Outsider

Max out Summon Outsider (lvl 16), you also need to +4 skill to reach level 20. Find equipment that gives you + x to all skills and also find a shrine of mastery. After that summon your outsider.


Dream

Have 12 enemies sleeping simultaneously

Max out Sands of Sleep.

Phantom Strike six enemies at once

Max out phatom strike/Dream Stealer.

Craft a Lesser Artefact

Craft a Greater Artefact

Craft a Divine Artefact

Complete 50 charms

Assemble 50 relics

Retrieve a relic from an item

Legendary difficulty gets unlocked after completing Epic difficulty. This will take you a very long time to get unless you use Tqdefiler and unlock Legendary difficulty right from the start.

Beat Legendary difficulty as a Warfare character

Beat Legendary difficulty as a Defense character

Beat Legendary difficulty as an Earth character

Beat Legendary difficulty as a Storm character

Beat Legendary difficulty as a Hunting character

Beat Legendary difficulty as a Rogue character

Beat Legendary difficulty as a Spirit character

Beat Legendary difficulty as a Nature character

Beat Legendary difficulty as a Dream character

These next achievements do not stack. You have to beat each difficulty with zero deaths to unlock the achievements.

Finish Normal difficulty with zero deaths

Finish Epic difficulty with zero deaths

Finish Legendary difficulty with zero deaths

Form a party with other heroes

Finish all 3 difficulties in less than 20 hours play time

This one requires you to play multiplayer in all 3 difficulties. Hopefully you can join games where most of the quests are complete and you can just finish the acts quickly.

Kill 100.000 monsters with a single character

A single playthrough will get you around 10-15 thousand enemies killed depending on how thorough you are in each area. This will take you a long time.

Kill a million monsters

This will most likely be your last achievement. Good luck.

Wear five matching set items

Reach level 2 without taking any damage

Using a bow or joining a multiplayer game will help.

Have a characer reach level 75

Finish Normal difficulty without selecting a second mastery

Finish Normal with less than 100 monsters killed

In order to accomplish this, your allies/traps have to kill the enemies for you. Nature/Spirit or Nautre/Rogue seems to be a good build. Put all points in summoning pets/traps and take things slowly. Equip any items that boost your pets. You are more than likely need to join multiplayer when you first start out so others kill the enemies for you so you can level up a few times without actually killing anybody.

Also: Credit to FericJaggar
Use Nature, summon wolves. You can use Dream too because the Nightmare pet boosts the stats of all pets summoned. And you let your minions doing the job for you, while you heal them.

Any help on these would be appreciated.



Magebreaker
Burn an enemy's mana for 2500 damage

The only skill related to this that I could find is spell breaker/spell shook.

- I tried this and it didn't work, any suggestions would be helpful.

I hope this makes it easier to search for achievements that you still need to get. If you see any mistakes or any suggestions in how to get any of these achievements, please let me know so that I can added it to the guide. Happy Gaming!