Blood Knight AI

[weakwarrior]

I was using firewall on some blood knights yesterday (as a mage in an IM game) and noticed that often they will try and avoid walking through firewalls, even if this means standing and waiting, but sometimes they will just walk through. This is pretty useful since they often stop right in front of the firewall in which case you can cast a second firewall right behind the first and they just stand in a firewall. This is more efficient than stonecurse and firewall because 1) it's cheaper (manawise) 2) firewalls last longer 3) 2 firewalls can fry more than one blood knight. I don't see anything in Jarulf which would explain this behavior (I looked in the skeleton AI section). Maybe they 'think' that a firewall is like a wall? But then why do they sometimes go through? Anyway, if someone could make this consistently repeatable it would be a pretty useful IM tactic.

[Zenda]

I'm not sure if this will work consistently in Diablo, but you could try placing two firewalls exactly on top of eachother. In HellFire, that will stop all non-immune monsters 100% of the time. Diablo seems to work a bit differently in this respect, though.

Why it doesn't always work (with a single wall), I cannot tell you. Part of the pathfinding code in HellFire checks every tile that needs to be passed for a Fire- or Lightning Wall effect, and considers such tiles as blocked when a monster is not immune. As far as I can tell, that should work good enough by itself, but experience learned that you actually need a double effect to make it reliable. Because of how this code works, Fire- and Lightning Walls (in HellFire) do not 'stack'. When both are on the same spot, the game will never consider the path blocked.

[FireIceTalon]

I was using firewall on some blood knights yesterday (as a mage in an IM game) and noticed that often they will try and avoid walking through firewalls, even if this means standing and waiting, but sometimes they will just walk through. This is pretty useful since they often stop right in front of the firewall in which case you can cast a second firewall right behind the first and they just stand in a firewall. This is more efficient than stonecurse and firewall because 1) it's cheaper (manawise) 2) firewalls last longer 3) 2 firewalls can fry more than one blood knight. I don't see anything in Jarulf which would explain this behavior (I looked in the skeleton AI section). Maybe they 'think' that a firewall is like a wall? But then why do they sometimes go through? Anyway, if someone could make this consistently repeatable it would be a pretty useful IM tactic.

Hi Weak,

I know exactly what you speak of, and for a while I couldnt understand it either, but it seems to have something to do with the amount of tiles between a particular hallway and/or passage. For example lets say you are on the east (or west) side of Diablo's cage and you have BK's chasing you. This is a pretty wide space, so if u cast a firewall directly in front of you, the knights will ignore it and go around and you get swarmed. However, if this takes place on the outside of cage 2 (the maze) on the east or west, this is a pretty narrow (2 tiles i believe) hallway and the knights will stop in front of the firewall, letting u take them out one by one while they get cooked. Next time you do hell/hell with your warrior, experiment on 16 in these 2 areas and you will see what I mean.

Cheers

[weakwarrior]

Hi all,

I tried stacking firewalls (even stacking 2 on one row and 2 on the next) in narrow spaces and sometimes they still walk through. I wish I could sort out exactly what is going on here

[Zenda]

Was that in Diablo? If so, that game apparantly lacks the pathfinding code I was talking about. Well, that means I have very little to add, since my knowledge is mostly limited to HellFire.

[weakwarrior]

Was that in Diablo? If so, that game apparantly lacks the pathfinding code I was talking about. Well, that means I have very little to add, since my knowledge is mostly limited to HellFire.

It was in diablo. The thing is sometimes they refuse to cross the firewall and sometimes they don't. Hell, sometimes some will cross and other won't (the same fw) so I would like to know how to make it so none do.

[the Langolier]

This firewall tactic works with any non-immune enemy. They will come up to a firewall and will not cross it except at the tile on which you cast the spell. They will always cross it at this location only. If there is an obstacle in that tile (such as a stone cursed enemy) they will not cross it at all. If there is room around the firewall, they will walk around it, but otherwise in a narrow hallway they have no other place to cross and will just wait. However, if you lay down two firewalls on top of each other, it won't work and they will just swarm over it like nothing was there.

A good way to use this tactic is to cast a firewall against non-fire immune enemies in a hallway directly in front of your feet and stand there. The enemies will group behind the wall while one steps into the firewall to engage you. It will stand in the firewall while attacking you, blocking the special tile they all want to enter. That will force all the ones behind it to pace behind the wall.

You can also lay a screen full of firewalls adjacent to each other and watch as they all cross slowly in single file. Just stand to block the way at the last one and watch them all sit there while roasting.

[weakwarrior]

...

Great help! Thanks.

[Galbraith]

This firewall tactic works with any non-immune enemy. They will come up to a firewall and will not cross it except at the tile on which you cast the spell. They will always cross it at this location only. If there is an obstacle in that tile (such as a stone cursed enemy) they will not cross it at all. If there is room around the firewall, they will walk around it, but otherwise in a narrow hallway they have no other place to cross and will just wait. However, if you lay down two firewalls on top of each other, it won't work and they will just swarm over it like nothing was there.

And why is that? (from technical point of view). Why there is only one not blocking spot, and it is not working after double-cast? And how this spot really work? How it is related with AI?

[weakwarrior]

Part 1:

This firewall tactic works with any non-immune enemy. They will come up to a firewall and will not cross it except at the tile on which you cast the spell. They will always cross it at this location only. If there is an obstacle in that tile (such as a stone cursed enemy) they will not cross it at all. If there is room around the firewall, they will walk around it, but otherwise in a narrow hallway they have no other place to cross and will just wait. However, if you lay down two firewalls on top of each other, it won't work and they will just swarm over it like nothing was there.

A good way to use this tactic is to cast a firewall against non-fire immune enemies in a hallway directly in front of your feet and stand there. The enemies will group behind the wall while one steps into the firewall to engage you. It will stand in the firewall while attacking you, blocking the special tile they all want to enter. That will force all the ones behind it to pace behind the wall.

You can also lay a screen full of firewalls adjacent to each other and watch as they all cross slowly in single file. Just stand to block the way at the last one and watch them all sit there while roasting.

This post of yours showed me I was misusing firewall for as long as I've been playing and, in case I'm not the only one, I'd like to explain how. First off let me just modify your post slightly. Monsters can cross a firewall as long as there are 2 effects going on on the same tile. The tile where you cast the firewall is considered to have 2 firewalls on it (1 moving right and the other left), which causes it to do 2x damage, and therefore monsters can cross. If you start shooting over a firewall monsters can cross where your arrows are, which can be a problem if your to-hit is low or you can't stun (IM players beware). Similarly, lightening demons who cast lightening, which is a pretty long spell, can cross behind their lightening casts, so beware as well.

(Edit: I showed this trick to Attika and after experimenting with it he pointed out that the flash spell, and as it also turns out the guardian from the guardian spell, do not have this effect.)

Now, because normally the only tile where monsters can cross is the casting tile if you have a grill you want to cast your fw on the other side of the grill offset fromt the door more than 1 tile. This way, monsters can step into your fw, but can't get to the door from there so they are stuck.



In the above situation I cast the fw on the gold. When I bring monsters



they simply stand in the firewall roasting. If many monsters had come I could cast a second firewall behind the first and then stack a 3rd firewall on the second. What this would do would be to allow the monsters to step into any tile of the second firewall. The fw adjacent to the grate, however, would only have one accessible tile and the monsters would not be able to pass the gate. I cast the firewall before getting monsters, but that isn't necessary - as long as you can cast your fws true.

This works because 1) there is a door 2) there is a gate.

[weakwarrior]

Part 2:

What if you only have a gate, which is what happens in catacombs and sometimes in the dungeon?

Well in a pinch, say an IM game where the scout awoke too many monsters or a boss, what you can do is cast the firewall on the outside of a door (see image below), more than 1 tile offset from the door and then cross the firewall and run into the room. The monsters will not follow and will roast. Again, you can always stack 2 firewalls behind the first if many monsters come.

[weakwarrior]

Part 3:

In hell there are no doors so you need to be a bit more creative. The reason you need a door is because it is a way to force all enemies onto a single tile. You can create a virtual door by casting a firewall since that itself forces them to one tile. In the image below I will cast a firewall on the gold in front of me, then take 3 steps down (along the axis of the firewall) and cast a second firewall on the gold there.



The bloodknights are then trapped as seen below.



Since there are so many of them I stack 2 firewalls behind the two shown above for quicker cooking.



In fact, you can park diablo using these 2 offset fws. All you need to do is to find a choke point. With my lvl 49 mage with lvl 18 fw, 2 firewalls is sufficient to kill diablo on hell diff. With my lvl 47 rogue with lvl 15 fw the fw drops before he dies, so I need to reset the fws. But with only 4 firewalls he drops just fine. And remember, diablo will stay in the fw even if you hide behind a wall to avoid the apoc blasts.

In cave-in-IM parking diablo is a real pain. Your low lvl fw will not kill him, but what you can do is have one character lead diablo past a choke point and then have a second one use the double firewall to block the way out. The person who led diablo now runs through the 2 fws and you have until the fw drops to create enough distance that diablo can't follow you before becoming inactive again. Then you can clear the 4th cage in peace.

Some final thoughts.
In the case of lightening demons their lightening will open up the firewall, so the 2x firewall won't work, but one firewall+gate will, since as long as you don't stand near the gate their lightening will never open the tiles near the gate, so they can't pass.

Remeber, fire-immune monsters walk right through.

In IM it may help to have a choke point setup with the gold preset for the ability to quickly setup a virtual wall when the going gets rough.

In a real pinch you don't need a choke point. You can use 3 firewalls to cover a huge distance as long as the entrance tiles are not adjacent to an open tile.

If you don´t have enough mana to cast more than 2 fw´s (IM games) and are worried that your firewalls will fall before you have killed everything off, you can shoot one arrow at a time, thus letting enemies across slowly and then kill them off.

To quote Gandolf "You cannot pass... I am a servant of the Secret Fire, wielder of the Flame of Anor. The Dark Flame will not avail you, Flame of Udun. Go back to the shadow. You shall not pass." Of course he was speaking to a balrog which could pass through these firewalls, but you get the idea.

[the Langolier]

Monsters can cross a firewall as long as there are 2 effects going on on the same tile.

Excellent post!

I never knew it was because two effects where going on on the same tile. I would sometimes notice that even with just one firewall cast monsters would cross, but didn't see the pattern.