Necromancy

Background information

Necromancy is one of many Secondary Skills. Unlike the other secondary skills, Necromancy is not learned. That is to say that only the Necropolis heroes Necromancers and Death Knights can normally have this skill, and each of them already starts with it. Witches were sometimes able to learn Necromancy when leveling, but this was changed in later versions. Non-necropolis heroes can learn Necromancy from Witch Huts or Scholars if the mapmakers allow it.

Recommended for: N/A. Necropolis heroes already start with Necromancy.

Description

When a hero wins a battle, a portion of the opposition killed is resurrected as skeletons and added to the hero's army.

• Basic effect: 10% of enemy battlefield dead are resurrected as Skeletons.
• Advanced effect: 20% of enemy battlefield dead are resurrected as Skeletons.
• Expert effect: 30% of enemy battlefield dead are resurrected as Skeletons.

Heroes with a specialty in this skill

• Isra the Death Knight
• Vidomina the Necromancer

Artifacts affecting this skill

• Amulet of the Undertaker
• Vampire's Cowl
• Dead Man's Boots
• Cloak of the Undead King

Buildings affecting this skill

• Necromancy Amplifier
• Soul prison

Additional information

If you don't have Skeletons or an empty army slot, but do have Skeleton warriors, you will get skeleton warriors, but only 2/3 of normal numbers.

In-depth

This is copied from http://www.heroescommunity.com/viewthread.php3?FID=6&TID=11784,
and originally written by angelito.  Edited for clarity.

Many times I thought about the necromancy skill and how it works exactly. When I read my "Heroes-updater-list", where there is described what was changed with which patch, there was a point about the "reworking" of that skill coming with the 1.3 patch. So I think since this version, that skill works fine and could be explained very easy (with one exception....but read that later...).

Basic

Some question had to be figured out:

Which necromancy skill counts, the one you have before you go into a fight, or the one which you have after the fight? Normally the level-up happens first, and then the result of the risen skeletons is shown.

After some testing, it's clear. The skill you have before you get into a fight is counted.

How do the necromancy bonuses count? Are they cumulative, or are they all based on your necromancy skill?

I also did some testing here. They are all cumulative.

That means that if you have expert necromancy, have built the Necromancy amplifier, and have the Vampire's Cowl, then your effective necromancy skill is 50%.

One exception

The skill specialty "Necromancy", like Isra has, is always based on the "natural" necromancy skill the hero has. That means, if Isra is level 20, his necromancy skill does NOT rise to 100%, but up to 80% (30% expert necromancy, 30% specialty (20*5% of 30), 10% amplifier, 10% Vampire's Cowl).

When I have expert necromancy (30%) and fight against a stack of 100 creatures, how come there are not exactly 30 skeletons raised after the fight?

This is the most misunderstood fact of this skill, and I think that is what is meant with the "reworking of that skill". The number of raised skeletons is not based on the number of creatures you are fighting, but rather on the total of their hit points! *

*This is not entirely true. Both Health and numbers are calculated, and the smaller of those are used. This means that numbers are the limiting factor in almost all cases.

Examples

Example 1

You fight against 1000 Gremlins and have expert necromancy. How many Skeletons will be raised?

• Total hit points of the gremlins were 1000*4 = 4000
• Expert necromancy means 30% of "hit points" will raise = 1200
• How many skeletons will you "get" for 1200 hit points?

Right...exactly 200.

Example 2

You fight against 30 Gremlins and have basic necromancy. How many Skeletons will be raised?

• Total hit points of the gremlins were 30*4 = 120
• Basic necromancy means 10% of "hit points" will raise = 12
• How many skeletons will you "get" for 12 hit points?

Exactly 2.

Example 3

You fight against 500 Gremlins and have expert necromancy, a Necromancy amplifier, the Amulet of the Undertaker, and Isra Level 10. How many Skeletons will be raised?

• Total hit points of the gremlins were 500*4 = 2000
• Expert necromancy (30%), Isra Level 10 (10*5% of 30% = 15%), amplifier (10%), amulet (5%); that makes 60%
• 60% of 2000 hit points = 1200 hit points.
• How many skeletons will you "get" for 1200 hit points?

Exactly 200.

Summary

So there are some points to notice:

• You can't raise more skeletons than the number of creatures you are fighting against.
• Your necromancy skill can't rise above 100%.

This fact is especially relevant when you play with Isra or Vidomina, who have necromancy as their specialty.

Take a look at this situation:
You are an expert necromancer, have all 3 necromancy artifacts (Amulet of the Undertaker, Vampire's Cowl, and Dead Man's Boots, but not as a combination artifact) and 2 towns where the Necromancy amplifier is built. That will give a total of 80% necromancy skill. When your hero now is Level 20, normally this number will rise to 110% (Level 20= 20*5% of 30 = 30%).
But that is not possible.

If you fight against 1000 gremlins with 100% necromancy skill, you will raise 666 skeletons (1000*4=4000, 4000/6=666). There is nothing you can do to raise this number of skeletons after that fight. (I made Isra a level 50 hero and he raised exactly 666 skeletons).

The 3 stack thing

But now I will mention the one exception I could not figure out.

When I did those test fights, the gremlins were split into 1 or 2 stacks (I fought with 100 Titans) and the calculations were all great, in theory and in practice. But sometimes, the gremlins were split into 3 stacks, and then the calculation did not work exactly: the number of risen skeletons was smaller than calculated.

So I tried to figure out when 1 or 2 stacks would appear and when there were more stacks of gremlins.

I tried it with nearly every number between 10 and 100. Only when there were 40 gremlins were they separated into 3 stacks. I tried 80, 120, 160... every time there were 2 stacks. I tried 400, 4000... every time 2 stacks (I changed the number of my titans, I changed the spreading... always the same). The next number I could figure out where the gremlins were split into 3 stacks was 2000 (I chose some random numbers and was lucky).

Here are the test results against a neutral stack of 40 gremlins (which were split in 3 stacks: 14, 13, and 13):

With basic necromancy, only 1 skeleton was raised after the fight (normally it would be at least 2: 40*4=160, 10% of 160=16; this makes 2 skeletons with 4 hit points left).

With expert necromancy, only 6 skeletons were raised after the fight (normally it would be exactly 8: 30% of 160 = 48; this makes exactly 8 skeletons).

Then I did the same fight against a hero with 40 gremlins:

Against 1 stack.............. 8 skeletons raised Against 2 stacks (20, 20).... 8 skeletons raised Against 3 stacks (14, 13, 13) 6 skeletons raised???

I tried it with more than 3 stacks (500 gremlins in 5 stacks to 100), and it works fine, exactly as calculated.

Tried it with different numbers per stack (4 times 100, 1 time 101), works fine also.

So there has to be a (for me) "unknown" factor when fighting against a stack of creatures which were split into 3 stacks... does anybody know this? Or it's just a bug. --Terra

I'm not quite sure, but I think the program may calculate each stack separately.

For example, let's look at the above 3-stack case. With expert necromacy, the stack of 14 skeleton gives you only 2 as: 14*4=56 hit points, 30% of 56 = 16.8; this makes 2 skeletons with 4.8 hit points left(or wasted..). Similarly, two stacks of 13 also give you only 2 each.

I'm not sure whether the program uses round-up or round-down, but This explains your question.

This seems a little bit ridiculous to you. However, in my opinion, this is something should be. For instance, you may fight with a force which consists of 40 gremlins (assuming one stack) and 1 titan. Then you will get 9 skeleton: 8 from one stack of 40 gremlins and 1 from one stack of one titan. So actually this is natural and `should be' to me. -- a Guest

Afterword

Please remember, that this calculation works only since version 1.3! Hope I helped some guys to figure out how they can raise 3000 skeletons on week 6...

Though I know necro is banned in the zone mostly, this could be interesting stuff for some of you.

So it is safe to conclude that Necromancy re-raises Skeletons equal to damage you caused required to fill up one Skeleton. As above, If you fight 4000 Gremlins with 4HP and your Necromancy is capped at 100%, you will re-raise 666 (Gremlin's 4HP X 1000 = 4000 / Skeleton's HP6 = 666 re-raised).