u/CMDR_Expendible

So there's very little information online about the new item changing powers, so I wanted to just put up the things I've noticed so far; this isn't perfect, or even particularly detailed, but I wanted to share what I can to help get you all started too.

When Can You Start Doing It

For Ascendant changes, as soon as you get to Kurnhold; complete Altar of Ascension quest, and Jornn The Runekeeper does the items, the altar next to him does the Ascendant difficulty settings.

For Suffix/Prefix and re-roll etc, it's a quest after Kurnhold, Kurn Solutions I think; once unlocked, any Inventor in the world can do it for you.

What Does It Require To Do

The Italics items are mostly from Ascended bosses and heroes; I have not tried on lower difficulty yet

For Ascendant;

2 Ashes of Awakening,
1 Aspect of Beronath,
1 Aetherial Mutagen
5 Soul Fragments
1 Celestial Lotus

To Re-Roll Ascendent

5 Soul Fragments

To Re-Roll Item Stats etc

Increasing levels of Iron and Ashes of Awakening

How Should You Do It?

This is my own impression, but because efficient farms will need to be discovered, you need to prioritise how you use the limited resources you get because all rolls are RANDOM. You cannot choose your target.

And the odds of getting one specific modifcation are incredibly low. Using a Medal as an example, on Grimtools we can see that there are 279 Prefixes, 162 Suffixes, and 166 potential Ascendant results, of which you get to roll one try at a time.

You get Ashes of Awakening much more commonly than anything else, so my suggestion for an upgrade path is;

• For non-Set etc items, try and get a Double or Triple Rare, for extra base stats. If you get one drop with the Prefix etc you want, this should become your main, because...

• Upgrade the Stats on an item first; this is the cheapest, easiest, and best bang-per-buck. The information online is old and wrong though, you cannot change the "weighting" etc and get new, different buffs, you can only change the value of the ones already on it (and mousing over the option seems to confirm this, "Alter the item's Seed, causing all of it's attribute values to roll again within their respective ranges); hold down CTRL on PC to see the full stats, and it will now show the range they can generate. Re-roll this until you get a result you are happy with.

• Meanwhile, save up for an Ascend on your items. You will likely roll rubbish but it is at least a buff. Give it to the stuff you're going to hang onto the longest first, as this is not an easy change to make

• There is no point getting a new duplicate item and ascending that to try and get an Ascend you want, as the odds remain 1 in XXX on that roll too. And Re-Rolls are much cheaper, costing only the 5 soul fragments. But don't re-roll your rubbish Ascends yet as the resources come in too slowly. Save the Soul Fragments to ascend the rest of your gear first, only re-rolling when you have everything with at least one, or have spare 10+ fragments but no Beronath yet, so you can risk a free roll.

• Do the Prefix/Suffix last; whilst it's not too bad in Iron costs, the escalating Ashes costs are better spent on stats, and the odds of getting what you want are looooow (1 in 279 as above. Damn it).

Brand new to Isaac, picked it up on the Summer Sale of course; just idly googling how it all works (Rebirth alone is incredibly new user unfriendly; are Item Identifications only in Repentence, or? Not being able to unmap Item ID off the gamepad is frustrating too, as it keeps turning off) and I got to trying to work out what each power up does... one of which involved googling "There's Options".

But nowhere seemed to reference what its a subtle joke about.

It's a very old Anti-Abortion slogan. Probably most famous as one of the punchlines in a Bill Hicks skit.

Considering the content matter, I was surprised it wasn't referenced in the Wikis etc. It's a dead baby joke again, by a comedian beloved by the edgier-than-thou crowd. Or is it common knowledge, but just not reflected by what Google could find? Either way, just thought I'd share for those who didn't know.

Crom, I have never Purged with you before, you have not the interest for it. And no one, not even you, understands why exactly it goes good or bad. Why it starts, or why it suddenly ends. All that matters is that some of us try and pass on what we suspect. Teamwork pleases you, so I am granting what I think I've worked out to the rest of mankind. Grant people wisdom! And the Devs don't make it more intelligible, to hell with Funcrom!

In other words, after sitting by myself, rummaging until I found some very specific youtube videos, and getting my own kill arena for the Purge mostly working, I wanted to pass on what I think is causing some of the bugs and annoyances. Now I'm not an expert, and I can't see the code to be certain, but these are the things I think are tripping people up.

Firstly, THE ERROR MESSAGES ARE WRONG. They're pointing to the wrong things. At least, a lot of the time.

"No Reachable Location For Purge"

This might make you think that it's an issue with placing the enemy camp. Perhaps, sometimes, maybe it is. Try starting it a few times and see if it can place the Purge Camp at least once. This will narrow down environmental issues; a rock doesn't have much of a social life and doesn't move around much, so you can eliminate environmental issues if you can start it one time. If you never can, well maybe it's the wrong spot for a base...

But now how the error message is wrong. We're all confused with how the computer can't see it can fit into the same space twice; that's not the issue I found though. It's ALSO the case that if the path the Purge has to take is too long in travel distance, it won't place, and throws you this confusing error message.

I discovered this by slowly moving the Treasure along the fixed path I'd built, until I could start it, but at one point it was iffy if it would, which gave away that it's something related to a variable regarding the path distance, not the layout of the map. Move it further and further along my fixed path, and it became easier to start; so Exiles is most likely trying to place the Camp based on a maximum calculated walk distance from the Treasure, but that varies if something that moves, like one of your Thralls or pets gets in the way.

Behold this highly detailed and scientific example of what I mean. It not be immediately obvious, because between just two points you'd think the calculated distance is always the same, but no, if suddenly an elephant appears along the calculation path, it's a slightly longer path to go around it, and that's what the game is judging on.

Now add in a lot more elephants etc as defenders, and you're gimping your own base as the game will throw a wobbly trying to work out all the potential paths. And this happens during a fight because;

"The Purge Can No Longer Pathfind".

This error message is accurate, but keyboard-smashingly vague. There's two elements here, and I spotted it because I saw Purges disappearing when a friend's Pets were blocking a door. The first part is that every model in game has a corresponding "box" around it, which is considered impassible. And of course, each differs considerably. Put those huge backpacks onto a Thrall for example, and it's now a very fat thing indeed. Being sensible, you might think of cheesing the event by sticking Fat Albert in a choke point so the AI can't easily get past him. But not only do devs not want to make it that easy, the more blocking bois you put in, the more potential paths around it have to be calculated and it will slowly choke your hardware on big events like these. At some uncertain point, the game throws this error when it thinks the path finding is becoming too impossible...

But I mentioned doorways; there's something very specific the game is doing, and this youtube video helped give away what it was. (Give Xevyr a like for that, chaps.)

The game is using Doorways as a way to simplify to the AI where to go. Not just using them as Point A, then the next door is Point B, but if Doorways in particular become blocked, it seems to be an absolute fail condition for the Purge. In the video above, notice where valid terrain is marked green, and the doorway acts as a link for the AI to go from one green area to the next, now imagine that the door goes red and thus breaks the link between the two and the Purge kicks you out.

It's NOT having a door placed in the doorway, or the door being closed; I checked for that, and the door is still valid (and considered smashable by the siege NPCs); it's specifically if something else moves in front of it and blocks any pathway past it. Yes Thralls can be killed, eventually if they're very good, but the longer they're stood there making hundreds of things check if they can pass it... so no, if you think of having your Thralls etc fighting near doors, which is sound tactics, you're much more likely to break your own purge because their impassible boxes risk blocking it enough to switch the Purge off. (The Purge mobs themselves don't seem to have this issue. You can cram as many of them into one spot as are sent, as far as I can tell). I'll come back to how to design around that, but before that the other, totally wrong error message;

"It's Too Hard To Reach Your Coffers From Outside Your Base".

This might make you think that there's a block somewhere. Or your elephant is just too damn mighty for the AI to think it'll be a fair fight...

Nope, this one is even more obscure. It's actually how much free space is around your Treasure chest. Really. This was confusing because sometimes it would start, and sometimes it wouldn't, and the treasure box is as antisocial as the rocks, it doesn't move about much either, so... huh? Then I twigged; it's YOU that's the variable. And the Thralls etc following you. It's trying to calculate getting to the coffer literally, can mobs stand next to it and loot, and if you stay there and watch the gump, or your pet comes running by at the wrong moment, at the exact moment it calculates there's less space now, not enough space, so "It's too hard to reach..."

Extend the space around the Coffer so there's lots of standing room. Originally my Treasure was on just the single block path to the stairs and it would work, sometimes; I added the 3 triangle floor and it hasn't failed so far. Fingers crossed more standing space will work for you too.

And so, putting it all together...

You CAN make this work, and you can have chokepoints, but you need to work around the limitations. Here's my current design, not perfect but it will do to illustrate the principles that should help you set up yours. They enter from the point where the Katana points, run a single windy path to the rear door where the Treasure is.

Try and fix the path to the Treasure as much as possible; the less the AI can wander about, the less likely to throw the above error messages. Design a controlled path first, then move the Treasure a shorter and shorter distance until you can reliably start it... In my example, it works where it is (just behind the final door, see above), but if it didn't, I would move it further into the snakey-mazey part of the path to find where the lazy Purgesters give up. If it fails, don't change the maze, trust the AI can see the path, work out first how much distance the AI is going to give you. And remember, going around is the same as going under or over the elephant; in my build, coincidentally but handy for screenshotting, the Treasure would not work in the exact same spot on the floor above or below, going up or down added just enough extra distance to trigger "No Reachable Location". Leaving the final door to the treasure on the same level saved enough though. Simplify, measure, then work around what you have.

Ideally, you use doorways to mark out to the AI where the path it needs to follow is. Note I have one at the start, and two at the end of the corridor; I was considering one midway along the corridor if the AI struggled, but so far once they're on it, they seem to be ok. But here's a simple illustration for how you can design to try and aid pushing the AI; I'm not a visual artist, sorry! And I'm guessing the logic, but it simple AI hasn't changed much in decades... So, in A.) let's say you put two doorways down, the two at the top of the triangle, to catch and redirect the AI from all over the map; however the top two Ds are closer to each other than each is to the one on the path to the Treasure. Bad design, red line path, the AI will lean towards the shorter path.

In B.) the Doorway on the path to the Treasure is closer than the top two are to each other; then when the AI goes down, each doorway again on the path is closer and closer to encourage a specific direction... Green design, good stuff.

Notice all my thralls aren't actually on the path itself, to avoid blocking it. And apart from the spikes to discourage climbing, there's nothing but a few torches along it to keep it simple and clean, and avoid unfortunate Pathfindile Dysfunction issues.

You CAN have mass fights, but make sure to do it away from doorways; for example, in the prior illustration of high art, you'd put your mobs in the triangle between the 3 Ds, lower down where the likely path narrows, but not near enough to any of the D's to risk blocking the door. Keep them away from doors.

In my build, they're all on a platform the AI can't reach at all, firing into the arena. To make sure they don't leap down and risk blocking shenanigans, these are my settings;

Combat Tactic: Hold. This makes stay exactly where placed. Following Behaviour: Passive. I don't know if Hold over-rides this, but just in case, ignore what I'm doing and stay put, you destards.

Guarding Behaviour: Aggressive. This makes them seek targets without waiting for aggro or my orders. They'll stand put and put out the dakka.

Follow: 5m. The shortest distance. Again, they shouldn't be moving, but if they do, they'll come to within 5m of me, and I'll at least know where they are and what they're doing. You could also set this to the maximum, so they stay as far away from you as possible, and thus away from the mobs and hopefully doors... but that might send them out of your carefully designed traps, and potentially into the Purge camp, and maybe when they lose aggro they'll try and return to their Guard point and back through doors again. My thinking is minimum, but feel free to experiment.

Attack: 15m Enough to have a decent range, but you don't want them to cover the whole arena. Set up staggered kill zones and let them focus. Tweak this depending on the size and shape of your arena; were the paths completely enclosed, a a maximum range to shoot along the corridor can also work, but I'll come back to why I went with the common open plan...

Chase: 15m. You can't drop this below their attack range, so you're stuck with this. Doesn't do much as they're ordered to stand still so no chasing Purgussy allowed, you horny thralls you.

You could also set up small kill boxes where the room is larger than the rough size of all the units inside in a single file line. Bigger boxes if you're using Elephants, natch. If you do that, set up as above, but drop Attack and Chase to 5m, so they don't move around much when fighting, then make the room 6m plus on all sides from where you place them, and hopefully they'll never be able to block the whole space. Very fiddly, very hard to set up well, so I wouldn't bother...

Instead, I take two Thralls into the path to fight with me. Because they need levelling, but to do that, they need different settings;

Combat Tactic: Withdraw. This keeps them moving AWAY from the NPCs, and thus they'll naturally try and avoid being stationary, and thus hopefully away from any checkpoints the NPCs are moving towards. Give them both Melee and Ranged weapons; they'll always try and Withdraw, and at a distance they'll switch to ranged automatically, but Melee weapons are handy in case they get stuck on something or get cornered, so they're not totally out of the fight.

Following Behaviour: Aggressive. They won't wait to see if I'm attacked or what I'm doing, they'll act on positioning without input.

Guarding Behaviour: Aggressive. They'll always seek targets to fight without me

Follow, Attack, Chase distance all on Maximum. Follow Max to keep them far from yourself; Spreading your chums out lowers the chance of you all clustering and blocking a Doorway. Attack Max, it's counterintuitive, but maximum because you want them to shoot at anyone they can see; this is why the whole floor is made up of barriers then can shoot over, the two Thralls down there act as general DPS, but more usefully, if they can shoot any target they can see, and they can engage at any range, they won't be moving around all that much either as there's always a valid target exactly where they currently are. But simultaneously, they're encouraged to move away from mobs and thus away from doorways and thus avoid being blocking barstools. Shorter attack range means they're more likely to try and close to maintain distance, and as the AI is moving towards you as well, too much potential for accidentally falling onto their Purge sticks and needing an uncomfortable trip to Accident and Emergency... but because you know the direction the mobs are coming, Away will almost always mean backwards down the path towards the Treasure, so they continue to be usefully defending. It all sounds contradictory, but it seems to work for me. And don't forget, as they're following you, you can quickly just send them a Move Here order (E Key on PC) to reset where they're standing.

I've currently only unlocked the Oil Cauldrons. Those torches inside the path? They're not just to give light, they mark roughly where the splash damage from the Cauldrons are, so I can let them do their thing then fight from outside the muck. I had more cauldrons in the middle walls originally but they covered so much of the arena it turned into a sluggish slideshow.

I'm also working my way up through the levels, so it's not a finalised design; the kinks in the wall are because I've not worked out yet which weapons etc are changing the Thrall model so they can't stand flush with the crenelations, but I need to be able to walk around them sometimes, if only to re-arm everyone! I also don't know what the exploding Golems on later purges will do to the walls; but my way forward seems clear... More archers. Better bows, better arrows. Despite the wall of text above, Keep It Simple, Cimmerian!

Hope all of this helps you folks out there.