It is common knowledge that QoT builds focusing on Shamblers and Sedna builds focusing on Yeti's are rather bad, whereas Lord Erebus builds focusing on Night Walkers re pretty good. Why is this? The following should provide some insight.

First, let's look at Shamblers and related skills. I'm ignoring Mulch which is very good, because it doesn't help the shamblers themselves become better.

Shambler
Base Health 675
Damage 30
Shot Delay = 1
Rate of Fire = 0.5 (1 shot per 2 seconds)

Summon Shambler is the key that creates Shamblers. Increasing levels in Shamblers causes the number you summon at one time to increase, but the maximum shamblers that can be alive are capped at the 2 and 4, (at rank 1 and 3 respectively). Additional levels of Summon Shambler reduce the amount of time and mana it takes you to acquire a full set of shamblers.


Summon Shambler
Rank Cost Summoned  Max  Cost/summoned   Level
1       450         1          2       450                      1
2       625         2          2       312.5                   4
3       625         2          4       312.5                   7
4       975         4          4       243.75                10

Entourage is the Damage and Health buffs for Shamblers.
Entourage
Rank Damage Health Level
1          10       250     2
2          20       500     5
3          30       750     8

Compost is an odd skill. It is very similiar to Oak's Spirit based buffs. The compost buff is a function of the number of enemy units killed recently. This counter increments by 1 when an enemy dies close to the QoT, and decreases by 1 every 9 seconds. For every 3 points on the counter you gain one rank in Compost. Compost has 3 available ranks, so the maximum bonus occurs at 9 kills. Additionally, with additional ranks in Compost you gain a bonus level of compost that activates whenever the counter first increments. For our intents and purposes I'm assuming that Compost is always at its max rank for calculations. This is not true in an actual game situation, you would have to start at your lowest rank and then advance up to the highest rank.

Compost
Rank Damage Health  Level
(1)         4        60         -
(2)         6       120        -
(3)         8       180        -
1(4)      10      240        2
2(5)      12      300        5
3(6)      14      360        8


Morale is the General specific buff, and is the same for all General demigods.

Morale
Rank RateOfFire Armor Damage Regen  Health  Level
1           2%        50          4       0.5      50          2
2           4%      100          8       1.0     100         4
3           6%      150        12       1.5     150         6
4           8%      200        16       2.0     200         8
5          10%     250        20       2.5     250        10
6          12%     300        24       3.0     300        15

Okay, now that I've listed all of the available abilities, let's consider what the Shamblers look like at the end of the game. I'm going to consider two builds, one build with max ranks in all abilities (Morale, Compost, Summon Shambler, and Entourage) the other has everything except Compost. The stats for these two builds are as follows. Note that Shamblers are ranged units that hit everything in a line between them and their target. I'm assuming that the Shambler is attacking a single target, with more available targets damage can increase, however there is no good way to express this.

Super Shamblers with Max Compost Level (All QoT minion abilities chosen)
Number Damage  DPS Health Armor  Total DPS  Skill Points
    4         98        55   2085    300        220           16

No Compost (All QoT minion abilities chosen, except compost)
Number Damage  DPS Health Armor  Total DPS  Skill Points
    4         84        47   1725    300       188            13
  
For the 3 extra points into Compost we gain 360 health  and 17% more damage. The health is somewhat trivial, the damage is decent, but to get and maintain that high of level of Compost is inconvienent. There is also the problem of having very few free points to be spent on other abilities.

Now, let's look into Lord Erebus's Night Walkers.

Night Walker
Base Health 720
Damage  20
RateOfFire 0.65 (1 shot per 1.54 seconds)

Without having to spend any ability points, Lord Erebus automatically has a maximum limit on Night Walkers of 2 and a 35% chance to create one after an enemy death. The aura says 20% but the lua says 35%. This gives him an advantage in that he pays nothing for Night Walkers, however there is the disadvantage of not being in control of when and how they are created. In most cases Night Walker levels are close to max, except after dying.

Improved Conversion Aura is how the spawn rate of Night Walkers is increased. It also increases health.

Improved Conversion Aura
Rank Chance Health  Level
0         35%        0      -
1         50%    100      2
2         65%    250      5
3         80%    400      8

Coven increases the damage and maximum number of Night Walkers.

Coven
Rank  Max   Damage  Level
0         2           0          -
1         6           6          2
2         8         12          5
3       10         18          8

Army of Night is a special level 15 skill that requries maximum ranks in both Improved Conversion Aura and Coven. It gives 5% more damage and 10% life drain to Night Walkers.

Army of the Night
Rank RateOfFire Lifedrain Level
1        5%       10%      15

Morale (6 ranks same as above)

To compare against our QoT builds, we have the following maximized Night Walker with full ranks into Morale, Improved Conversion Aura, Coven, and Army of the Night.

Super  Night Walker (All Erebus minion abilities chosen)
Number Damage  DPS Health Armor  Total DPS  Skill Points  LifeDrain
    10        62       47    1420   300        470           13          10%**

  **(This can be increased with other abilities. +10% more from Vampiric Aura & up to +65 Health/second from Mist)

Now, comparing the builds to each other. Also note that these builds require Morale 6 and Army of the Night which are both level 15 skills.

Super  Night Walker (All Erebus minion abilities chosen)
Number Damage  DPS Health Armor  Total DPS  Skill Points  LifeDrain
    10        62       47    1420   300        470           13          10%**

Super Shamblers with Max Compost Level (All QoT minion abilities chosen)
Number Damage  DPS Health Armor  Total DPS  Skill Points
    4         98        55   2085    300        220           16

No Compost (All QoT minion abilities chosen, except compost)
Number Damage  DPS Health Armor  Total DPS  Skill Points
    4         84        47   1725    300       188            13

Comparisons:
Comparing the 13 Skill Point builds, Night Walkers do 250% damage per second compared to Shamblers. Armor levels are identical. Shamblers have higher health than Night Walkers, however Night Walkers have access to large amount of health regeneration and life steal. For effective Health, I would call them roughly equivalent.  Summoning is very different. Night Walkers are automatically created as a function of creep combat without any necessary intervention, whereas Shamblers must be summoned which costs mana. I believe this to be a huge advantage to Night Walkers. In numbers, there are 6 more Night Walkers than Shamblers. Comparing the QoT with Compost versus the Night Walker build the damage advantage is reduced to only 213%, and all other comparisons are relatively the same.

Neither QoT or Lord Erebus has difficulties with creep waves, so the best comparison is vs other Demigods in a 1 on 1 battle. In this situation the Multihit capacity of Shamblers is ineffective, so the DPS numbers are relatively accurate. The number of Night Walkers brought the to the battle will vary, however it will tend to be close to max. The Shamblers do still have the range advantage, however in most cases combat occurs at melee range regardless.

Summary:
At the individual minion level, Shamblers and Night Walkers are very similiar. They have similar DPS, effective health, and armor. However, because of the higher maximum number of Night Walkers versus Shamblers, the Night Walkers have a clear advantage. Changing the number of points spent on abilities doesn't really change this relationship. Additionally, the cost of creating Shamblers is relatively mana expensive given the high mana usage of the QoT. Lastly, the attention necessary to monitor the number of active Shamblers further taxes the QoT's combat abilities.

Itemization also favors Lord Erebus. Night Walkers typically outnumber shamblers and they have a higher attack speed. Night Walkers attack 30% faster than Shamblers, which means 30% more damage from +damage items. Likewise, there are more Night Walkers than Shamblers, at maximium levels 150% more. Thus +Attack Rate and +damage items will benefit the Night Walkers 150% than the shamblers based on numbers alone (4 versus 10).

At this point we must also mention other idol minions, priests, minotaurs, and siege units. Erebus and QoT have equal access to them, which is why I have discounted them until now. However their presence dillutes the effect of items some, so that a QoT will have a maximum of 10 minions (4 shamblers, 2 priests, 2 siege units, 2 minotaurs), whereas an Erebus can have a maximum of 16 mininons. It may prove advantageous for an Erebus to invest in Items with +minion stats, in contrast to a QoT who may find idols a better buy. However, this requires further calculation.

In closing the advantage of the Erebus comes mainly from the pure number of minions. This is further compounded by items which reward the quantity of minions rather than the quality. This may be balanced out by the area attack of the shambler, however since versus demigod combat is the most important measure of combat utility, this is doubtful. Additionally, if minion control UI improvements are made it may be possible to micromanage minions more easily. This would greatly help the QoT much more than the Erebus, and this may bring additional balance.

The following are a few additional things to consider.

• QoT's Spike Burst and Erebus's Bite lower armor and increase the damage.
• QoT's level 15 minion skill is Tribute which gives +4 gold per second, which grants an economic advantage compared to Lord Erebus's Army of Night which grants a combat advantage.
• Shamblers are ranged units and do damage to all units between them and their target. Their range is equal to that of the priest creeps.
• Night Walkers are melee units and possess rather weak AI's.
• Compost increases the damage of Uproot (which is argueably a bad skill).
• Compost requires continuously killing to maintain (every 9 seconds).
• Shamblers currently suffer from a targetting bug, it can be fixed with a single line of code.
  
• QoT currently suffers from not summoning minions are full health due to the Drop/Pickup health/mana items fix.

Given all this there is a clear advantage to the Night Walkers at least at maximized skill levels, however most games depend upon the early levels, so more useful comparisons can come from looking into these levels. Given the vast array of information to compare, I'm switching to charts to display the relevant information.

I'm going to compared 14 different builds, 7 builds for QoT and 7 for Erebus.

The QoT Builds are:
QoT : A QoT build with maximum levels in Summon Shambler.
QoT Entourage : A QoT build with maximum levels in Entourage.
QoT Morale : A QoT build with maximum levels in Morale.
QoT Compost : A QoT build with maximum levels in Compost at the maximum rank for that level of Compost. This assumes you always have a maximized kill count.
QoT Entourage + Morale : A QoT build with maximum levels in Entourage and Morale.
QoT Entourage + Compost : A QoT build with maximum levels in Entourage and Compost (again maxed rank of Compost).
QoT Morale + Compost : A QoT build with maximum levels in Morale and Compost (again maxed rank of Compost).
QoT Entourage + Morale + Compost : A QoT build with maximum levels in Entourage, Morale, and Compost (again maxed rank of Compost).

The pattern is the same for the Erebus builds.

The Erebus Builds:
Erebus : An Erebus build with no abilities.
Erebus Conversion  : An Erebus build with maximum levels in Improved Conversion Aura.
Erebus Coven  : An Erebus build with maximum levels in Coven.
Erebus Morale   : An Erebus build with maximum levels in Morale.
Erebus Conversion + Coven  : An Erebus build with maximum levels in Improved Conversion Aura and Coven, additionally at level 15 it gains Army of the Night.
Erebus Conversion + Morale  : An Erebus build with maximum levels in Improved Conversion Aura and Morale.
Erebus Coven + Morale  : An Erebus build with maximum levels in Coven and Morale.
Erebus Conversion + Coven + Morale  : An Erebus build with maximum levels in Improved Conversion Aura, Morale, and Coven, additionally at level 15 it gains Army of the Night.

The charts are relatively straightforward. I'm needing to go deal with dinner now, so I'm going to leave this at it stands until I get time to work on it more. Of particular interest is how the QoT has to invest in well-rounded Shamblers whereas Lord Erebus can focus on increasing the net damage done by his Night Walkers purely by focusing on Coven.