El Shaddai: Ascension of the Metatron

For this achievement, you must locate shades of a woman who will lead you a short distance and open a black swirling portal into "The Darkness." In these sections, there is a lake of darkness slowly rising, and you jump up ledges to stay above it- if you fall in it, it is game over, and it triggers STUPIDLY long, unskippable cutscene for this particular game over- cool the first time, but after that... argh. To ultimately escape from the darkness you must reach a ghostly woman usually fairly high up, if not at the very top, and she will pull you back outside the portal.

Now to obtain the entries themselves, you have to find the bones of Ishtar in each Darkness area- there is one per portal, with a total of six. You'll get a short look at them as you start your ascent, although you really can't navigate to them based on that little peek, because the footholds and ledges all look very very similar. Your ultimate objective is to grab the bones of ishtar, which look sortve like green leaves/floating green crystal fragments. They're very easy to pick out since everything else is grey/black and they are bright green. And once you grab them, you need to escape with them.

Despite the horrible consequences of falling into the darkness, the upside is that even if you do not happen to come across the bones on your way up, as long as you touch the woman's shade who pulls you out, you'll be right back outside the portal, and can go back in and try looking for them again as many times as you want. Err on the side of caution and keep ahead of the darkness while covering as much ground as you can by circling the walls of the darkness areas looking for the bones. Trying to press your luck checking everywhere and accidently falling into the darkness is really a fate worse than death, due to the load times involved, etc. Just keep doing runs up the areas until you manage to find them, and then keep going up until you find a shade. Pretty simple. Once you obtain the bone for a particular portal, the portal will not appear again, and you do not have to get all of the bones on one continuous playthrough- you can load up previous saves etc to grab the bone, and it is recorded in the master collection on the main menu.

The chapters you find the darkness portals are as follows:
Chapter 2 (The Tower) - After getting your first Gale, you will keep progressing a ways, and fight a few more fights, but make sure you hold on to a Gale. You will come to a section where there is a rotating pillar thing with two platforms attached to it like fan blades, sortve. The first one you will come to will be in motion, and you just have to cross it. Not too far past that, you will come to a split in the path, and if you look down the left path you will see another fan-platform construction but it is NOT moving yet. If you take fork in the path to the right you come to a switch, which, if you hit it, it will cause the second platform rotator to spin like the one before. The best way I've found to handle this is NOT to hit the switch yet. If you go up to the edge, double jump, then hit right bumper and A to do an air-dash with the gale, you can -barely- make it onto the center of the rotating platform thing, that isn't rotating yet (if you haven't hit the switch). The reason we didn't want to hit the switch, is because now it is perfectly aligned that if you walk out to the right, you can do another double jump and then an air dash and land on a small bridge section to the right, where a shade will becon you an open the first darkness portal. The jumps here are a little tricky, and when the thing is in motion, they get even harder to judge. After getting the ishtar bone from the portal, you'll probably have to jump back and hit the switch (which will be difficult as it's a blind jump, but you'll have the bone either way). If you just can't seem to make it, you can quit out to the main menu, and load your autosave, and it should put you on the platform before the immobile fan-platform thing and you can just go back and whack the switch. (even if you abandon a save, you still retain credit for ishtar bones/free-men notes in the library, which in turn count toward the achievement - you dont have to finish a chapter or manually save after getting them).

Chapter 3 (The Mercy of Ezekiel / Ezekiel's Realm) - This one is very easy to miss. After fighting Watcher Sariel, win or lose- it doesn't matter, you will proceed, and jump across some platforms that float up as you approach, and there are red wisps flying around, and once you cross this set of 6 platforms, you'll be at the start of a new section with a solid floor- instead of going ahead the obvious route, jump up on the top of the "tunnel" and you'll land on a little flat path on top of the structure, which if you follow will lead up to the apex where a shade will appear and beckon you into the darkness portal. If you get to a part where Nanna hops up some platforms after saying "This way, follow me!' you've gone too far.

Chapter 4 (Sariel's Deception / Sariel's Realm) - This one is pretty hard to miss. It is very near the final Lucifel save point on the 4th floor before you fight the true Sariel. Lucifel says "Hey, we just got back. Of course he'll do it - he wouldn't want to disappoint Uriel." The portal is right around here. (not up the staircase)

Chapter 5 (The Tragedy of Baraqel / Baraqel's Realm) - Progress a fair way through the stage and you will be forced to fight Watcher Ezekiel. Win or lose - it doesn't matter, then start climbing the outcrops on the cliff-like path ahead of you. On the 4 step up, you will be able to walk around the right side and the camera will swivel out to show a hidden alcove where a shade will beckon you to the darkness portal in this chapter.

Chapter 7 (The Cry of Armaros / Armaros' Realm) - Begin the chapter, fight the first group of enemies and proceed until there is a short scene where you see Nanna (the child) riding on a Nephilim hopping up some pillars. Instead of following her, loook to your left and there will be a tier'd blue tower-like structure- the portal is at the top.

Chapter 10 (The Grave of Arakiel / Arakiel's Realm) - Just after the Lucifel save point where he says "Hey, why don't you take a break? I could take over down here." you will come to a section with groups of 3 blocks with orange glowing marks that flip under themselves to form odd moving platforms of sorts- you'll want to ride along them until they take you to the left, where you'll see a floating grey platform that looks like a standard floor. Hop off onto it, and keep going left, and you'll get to a platform with a shade who will open the darkness portal. There are also a bunch of plants on this island surrounding the portal you can break for life/boost pick-ups, as a reference.

I found a Wonderfull Video on Youtube showing all Portal Locations.. and the Bones itself inside the Darkness Levels. Follow this Video and you will get your Isthar Bones without having to much Trouble :).

Credit goes to MrFethennour on Youtube.