Bone Necromancer Starting Guide
Most Important Stats: Faster Cast Rate (48% at this point would be fantastic), Strength to wear a larger belt & Energy for more Mana - rest into Vitality
Necromancers are a very slow class to start and one that most people consider painfully boring. For the first talent you'll want to get Teeth which gives you a way to attack other than melee and a Summoned Skeleton. Most people typically keep dumping points into Teeth until Level 6 at which point they get a Clay Golem which helps tank for them.
The downside of doing this is you need to carry around a full belt and full inventory of Mana Potions if you plan to upkeep the mana costs of Teeth. What I prefer to do is 1 point into Teeth then 3 points into Summon Skeleton followed by another point into Teeth. This covers the first 5 levels pretty well.
Important Teeth Information: The way Teeth works is the closer your cursor to your character the larger the Teeth spread. When your cursor is further away your Teeth shots are much more clustered together.
Early Tip: Browse Akara in Rogue Encampment for a Wand with +1 or +2 to Teeth
Use my screenshot above if you'd like to take a look at how your inventory should look potion wise. Basically you want to carry a few Stamina Potions for the long runs through dangerous areas, 4 or 5 Health Potions just incase you run into trouble and none are on the ground and fill up every other slot in both your inventory and belt with Mana Potions.
Aside from Potions you will occasionally want to pick up items with high vendor value to make some gold. Usually you'll need to consume Potions to make room for these items in your inventory along with frequent trips to town to sell and restock on more Potions.
Levels 1 - 10 Talents:
3 into Summon Skeleton
2 into Teeth
(Level 6) 1 point into Clay Golem (get immediately at level 6)
Teeth (all other points here)
If you'd like to level very fast on your Necromancer without much effort at all I would recommend you go to Cold Plains and Stony Field. You'll find very large groups of Fallen enemies in both of these zones (pictured below) that you can very easily AFK and kill. This is my favorite way to level up a Necromancer since there is no other class that can do it.
You can also buy Corpse Explosion early on if you decide to go this route which is the key rotation of the Summoner build. I honestly prefer this build to the one I am doing with this guide however it is painfully boring for people who actually want to play the game and not constantly alt tab and do something else like watch TV. I'm usually always alt tabbing to write guides or work on something so the Summoner build early on works better for me personally.
Quick Potion Buying Tip: Shift right click at a vendor to fill your entire belt with that type of Potion (any slot with a different Potion type will not fill). Then unequip your Belt to add all the Potions you bought to your inventory. The bigger your belt is the faster it will be to quickly add Potions to your inventory. This will save you a lot of time since buying them one by one is extremely slow.
The best pack of mobs for afk killing.
When you get into your early teens you'll notice yourself running out of mana more and more if you dump all of your points into Teeth, this is when you'll be faced with a decision on what to do. You can keep dumping more points into Teeth which is going to increase the mana cost or you can start putting some points into Skeletal Mastery and Raise Skeleton.
Once my Teeth gets to 11 I typically purchase Amplify Damage and Iron Maiden then start investing all additional points into Raise Skeleton and Skeletal Mastery. Since I dislike constant trips to town and doing full inventories of Mana Potions I prefer this route.
Amplify Damage you're putting a single point into in order to unlock Iron Maiden which is very useful for all of the boss fights during Normal. With this ability you can easily defeat Andariel, Duriel, Mephisto, Diablo and Baal with the "quit hitting yourself" method.
Note: If this is your first character and you have no twink gear it is strongly recommended you farm The Countess a few times for Runes. Tal and Eth are the two main ones that you're going to want to hang onto as they're used to make the Stealth Rune Word. Other than those two Runes all you need is a chest armor with 2 open Sockets. This item is the single biggest upgrade that you can get your character at this point.
Levels 11 - 20 Talents:
4 into Teeth
1 Skeleton Mastery (Helpful if you have +Skills)
1 Amplify Damage
1 Iron Maiden
1 into Corpse Explosion
1 into (Level 18) Bone Spear
Level 18 Bone Spear: This will be your new primary attack once you obtain it for single target enemies. Teeth is better for large spaced out crowds of monsters but Bone Spear is best for single target or when the enemies are clumped together enough and it penetrates through all of them.
You will be between levels 17 - 20 when you get to Andariel depending on whether or not you stopped to kill a lot of mobs and decided to do all of the quests during Act 1. So long as you are at least level 16 Andariel should not be that much of a problem. The best strategy you can use for her is to cast Iron Maiden on her then keep summoning Skeletons or Clay Golems as she kills them. Andariel will end up killing herself with the damage she does to your minions. That's all there is to it, just make sure you have enough Mana to keep summoning!
If you don't have Iron Maiden at this point that's ok, Andariel is easy enough to take out with just spamming Teeth or Bone Spear too... Just make sure you invest a point into Iron Maiden before we fight Duriel in Act 2 as the ability is much more useful on him. For more information on the Andariel fight check out my quest walkthrough (link below).
With Andariel out of the way we can begin Act 2. At this point in time you should have both Teeth and Bone Spear on your character and which one you should use depends pretty much entirely on personal preference. Bone Spear is nice when you're in close quarters and fighting enemies all bunched together in a line because it penetrates through all of them. If enemies are very spaced out in an open area then typically Teeth is better.
Make sure you do Act 2 Quest 1: Radament's Lair as early as possible since your reward for completing it is a Book of Skill which gives you a Skill Point.