Cloak of displacement versus protection late in game

[Bobby Durrett]

I built a simple test to try to see what difference a cloak of
protection made versus a cloak of displacement in the end game with
respect to magic cancellation. I setup a character in 3.6.1 in wizard
mode with -40 AC, speed boots, and high luck. I got a vampire lord next
to me and hit the . key 1000 times. I did this test twice, once with
displacement, once with protection. Out of the 1000 times I lost a level
34 times with displacement and 10 times with protection. I think that
this is about a 3.4% chance per turn of losing a level with displacement
and 1% chance with protection. I'm not sure how much this matters at the
end of the game because vampire lords don't last long in combat with a
well equipped character. And, you get the level back when you kill them.
I did this test manually so it isn't perfect. FWIW

Bobby

[David Damerell]

Quoting Bobby Durrett <net...@bobbydurrettdba.com>:
>I built a simple test to try to see what difference a cloak of
>protection made versus a cloak of displacement in the end game with
>respect to magic cancellation.

Wouldn't it have been easier just to look at the source?
--
David Damerell <dame...@chiark.greenend.org.uk> Kill the tomato!
Today is Second Friday, Presuary.
Tomorrow will be Second Saturday, Presuary - a weekend.

[jim in austin]

On Saturday, July 7, 2018 at 7:14:13 PM UTC-5, David Damerell wrote:
> Wouldn't it have been easier just to look at the source?

Well yeah, assuming you can understand the source. Otherwise, trial and
error. Whatever works...

[Bobby Durrett]

On 7/7/2018 5:14 PM, David Damerell wrote:
> Quoting Bobby Durrett <net...@bobbydurrettdba.com>:
>> I built a simple test to try to see what difference a cloak of
>> protection made versus a cloak of displacement in the end game with
>> respect to magic cancellation.
>
> Wouldn't it have been easier just to look at the source?
>

I guess I was thinking that I would have to look at a number of places
in the source code to get the overall percent chance of losing a level.
I would have to figure out the chance of being hit and how my speed
boots affected the chance that the monster even gets a chance to move, etc.

But, if I did examine the source and understand it correctly then I
could calculate the percentages directly instead of using testing which
involves randomness so that would be better.

I think the big problem with my test is that it didn't really test what
I wanted. I wanted to see the value of displacement compared to the
value of MC 3. But, I had my character stand still. Maybe I should have
it move around the V each time so that it misses due to displacement
some of the time.

Bobby

[Bobby Durrett]

I redid these tests with movement. Instead of hitting . every time I
moved back and forth adjacent to the V vampire lord. With movement I
only lost 25 levels with displacement instead of 34 standing still. With
movement I lost 9 levels with protection which is about the same as the
10 lost standing still. So with displacement you have 2.5%-3.4% chance
of losing a level when next to a vampire lord compared to .9%-1% chance
with protection. Maybe you could round that to overall 3% for
displacement and 1% for protection. 3 times worse for displacement but
the overall percentage chance of losing a level is small.

Bobby

[magicby...@yahoo.com]

It's not so simple.

Displacement is way, way, way better in the early game. Displacement is basically like having another set of armor class in the early game. First the low level enemy has to get by displacement (which they are bad at), then they have to hit your armor class. Displacement is by far superior in the early game, as well in the early game monsters don't have a lot of special attacks that magic cancellation is good against.

In the late game Cloak of Protection (particularly in 3.6.1) is a complete MONSTER. It's really the best. First of all it gives you an additional AC that no other cloak can give and is one of the few things that gives magic cancellation 3.

In the late game more and more monsters will be able to easily get through displacement if I'm not mistaken and you want MC3 for all sorts of special attacks that you will begin to encounter.

The starting cloak of displacement for Rangers are one of the few reasons they can survive the early game. Early monsters run in circles trying to find their image while the Ranger picks them off with arrows.

[Pat Rankin]

On Saturday, July 7, 2018 at 9:56:22 PM UTC-7, Bobby Durrett wrote:
> I redid these tests with movement. Instead of hitting . every time I

> moved back and forth adjacent to the V vampire lord. [...]

The effect of displacement is actually pretty tricky. In general, it is more
effective when you're moving, especially when multiple monsters are
trying to target you. The longer that you remain it one spot, the more
likely they are to figure out that spot. Once they do, they don't forget.

If the attacker failed to correctly guess your position on its previous move,
it will have to guess again on its new move _unless_ you happen to have
moved into the spot that it guessed on its previous move. So that's one
exception to the general case about being more effective when you're
moving.

If it did correctly guess on its previous move, it won't bother guessing on
its new move if you're still at that spot; it will just target your true location.
Note that if you are moving faster than the attacker and move away from
a correct guess, then move back before it had a chance to make another
move, it will be as if you hadn't moved at all--the old guess will 'still' be
correct and it will just attack. That's the other exception to the general
case about moving.

Digressing from displacement to MC... note that cloak of displacement
was already only MC2 in 3.4.3 and earlier versions. It's been downgraded
to MC1 in 3.6.x. Cloaks of invisibility, cloak of magic resistance, and elven
cloak were downgraded from MC3 to MC1. Oilskin cloak, robe, plate mail
(ordinary and crystal), and mithril-coats (both types) were downgraded
from MC3 to MC2. Cloak of protection has become the only way to get
MC3 from a single item, but wearing at least one ring of protection boosts
MC by 1 (unless it is already at 3). Wearing a second such ring does not
give a second boost. Eating such rings while polymorphed or receiving
divine protection affects AC and increases minimum MC from 0 to 1 but
does not otherwise enhance MC. I don't recall offhand whether ring of
protection stacks with that increased minimum or just duplicates it.

Enlightenment and end of game disclosure now report this previously
hidden form of protection so it is feasible to figure out that it exists.
Working out how to acquire is harder, and figuring out what it accomplishes
is still a blackbox.

[magicby...@yahoo.com]

SO it seems like if you have displacement the best course of action would be

@k

^In this position facing a kobold hit them with melee until they hit
you. then if they hit you then move to

k
@

Then stay in this position until they hit you. Then if they hit you move to here:

k
@

And so forth, in order to maximise the usefulness of displacement.

With missile weapon

@------->k

Keep firing and stand still until they get close.

@k

If they are this close, still fire if they miss. Once they hit, take one step back.

@ k

Now fire missle weapon and they will either 1. Swing at air and miss, or 2. Advance to as follows:

@k

If they are here again shoot until they hit and repeat. If you run out of room backing up then go around and out other side.

@k k k k k@ k @
@ @ @

And then again fire from a distance there.

The above can also be used to run past enemies as well.

I'd assume the displacement effect means the monster has a 1/4 or 1/8 chance of hitting the correct square. So I think at low levels if you use it as above it's extremely strong.

Displacement seems to stop working at higher and higher levels. Anyone have any intel on displacement PLUS invisibility?

[Pat Rankin]

On Sunday, July 22, 2018 at 11:57:52 AM UTC-7, magicby...@yahoo.com wrote:
> I'd assume the displacement effect means the monster has a 1/4
> or 1/8 chance of hitting the correct square. So I think at low levels
> if you use it as above it's extremely strong.

When displaced, there is a 25% chance that it will discover your location
without guessing. When invisible or otherwise unseen (ie, blinded monster),
the chance is 33%. If the chance fails, then the monster will guess. For
unseen, the guess uses a radius of one around your actual location; for
displaced, the radius is two so much less likely to find the right spot. The
guessing rejects locations that aren't within line-of-sight of you and some
other restrictions so concealment is less effective in corridors or near walls.

Since the guess might happen to find your spot, the chance to find you is
slightly higher than the 25% and 33% values mentioned above. Ranged
attackers might hit you even when they've guessed wrong, if their guess
happens to be lined up with your actual position.

> Displacement seems to stop working at higher and higher levels. Anyone
> have any intel on displacement PLUS invisibility?

I think that the only monsters not affected by displacement are shopkeepers
and temple priests. But when multiple monsters are present, each has its
own idea about where you are, so some will probably pinpoint you sooner
than others.

Having both invisibility and displacement is worse than displacement alone,
because monsters who can't see invisible will be trying to overcome the
weaker form of concealment. Put another way, if they can't see you then
they're unaware of displacement and not affected by it.