In all of my guides for builds I frequently refer to the early game, mid game, and end game. For my purposes, these references relate to specific levels...

Early Game = level 1 to 30

Mid Game = level 31 to 70

End Game = level 71 to 100.


Regarding skills...
I frequently mention the stats of certain skills in these builds. Be aware that usually I am referring to the max 15/15 points for a skill, or at least the max points used in a particular skill for a build. If you would like additional clarification about certain skills please ask me and I will add it to the guide.


Please let me know if there is additional terminology you would like clarified and I will add it to my guides.

Thanks!

This entire build is based on the Synergies Mod. I feel that this mod is a good improvement of the core game without breaking the game and making it too easy. Most of the information in this guide is still viable with the core game, but certain details are likely to be different. If you haven't tried the Synergies Mod you should check it out! You won't regret it!!

Strength - 325

Dexterity - 30

Focus - 80

Vitality - 100


STRENGTH
This is a ranged dps build, so Strength is the main skill here. With high Strength and certain skills, this build easily gets crits over 25K. Strength is what determines the amount of extra crit damage, and most of the stat points should go into Strength and Focus in the early game.

DEXTERITY
It's tempting to put more points into Dexterity, but it's really not necessary. With the proper gear this build should have at least a 30% crit chance and a 25% dodge chance near the endgame. Because this build has such a fast attack speed, a higher crit chance really isn't necessary. Put points into this stat gradually. One point each level until you get 30 is the best option.

FOCUS
This build is extremely mana dependent, and its main attacks also benefit from increased magic damage. Near the endgame you should have at least 300 mana points. Since natural mana regen is based on the total amount of mana you have, a high focus will help quickly fill up your mana after a series of attacks. With 2 or 3 mana regen gems, it's unlikely you will need to use mana potions very often unless you suffer from a mana drain attack. You're going to need plenty of mana starting from the very beginning, so you should almost always put at least 1 or 2 points into Focus each level until you reach 80 points. The sooner you reach 80 Focus, the easier it will be to maintain constant attacks without needing to use mana potions.

VITALITY
This is not a glass cannon build. Since this build doesn't use the Bulwark skill, the extra Vitality helps to boost armor value and elemental resistances. It also increases the odds of surviving more than just one hit by hero mobs and bosses in the endgame. Vitality is not too important in the early game, but you will need all of it before completing your first run through all the acts. At some levels you may even want to put all 5 points into Vitality until you reach 100. With the proper gear, enchantments and gems, you should end up with at least 150 Vitality.

BLITZ - 30

Heavy Lifting - 15/15

Coup de Grace - 15/15

HEAVY LIFTING
This skill is one of the keys to the power of this build. However you shouldn't put points into Heavy Lifting until a few other important skills have a solid foundation. This is more of a mid and end game skill.

COUP DE GRACE
This skill is based on your total amount of Strength, so it's pretty weak in the early game. In the mid and end game this skill really shines, especially against hero mobs that can be stunned. Some players argue that the 1 second cooldown for Coup de Grace makes it "worthless", but thats not my experience at all. Extra strength or +X% to electric damage will add even more damage to Coup de Grace. Imho this skill totally wrecks hero and elite mobs. Basically, Coup de Grace can turn even a non-crit hit into a nice bit of burst damage, and burst damage, with crits or other means, is what you need to kill mobs fast.


CONSTRUCTION - 72

Healing Bot - 15/15

Blast Cannon - 15/15

Fusillade - 15/15

Fire and Spark - 15/15

Charge Domination - 12/15

HEALING BOT
This skill is critical to your survival and should be one of the first skills that gets points. The full 15 points is necessary for the mana regen and the armor boost. This build is mana intensive, so the mana regen is crucial. This build also doesn't use the Bulwark skill, so the armor boost is a solid benefit.

BLAST CANNON
This skill is the bread and butter of this build until Fusillade develops much later. Put points into this skill immediately and continue to do so until you have 15. The chance to blind enemies is awesome, especially versus strong melee hero mobs. Often times you can practically lock down mobs with the Blindness effect from Blast Cannon. Be aware that bosses are almost always immune to Blindness, but it works great against lesser mobs. When you need to clear out a horde of mobs all packed together, Blast Cannon does the job perfectly. Whenever possible you should position yourself to line up as many targets as possible with Blast Cannon because it penetrates through mobs.

FUSILLADE
This skill is a big reason why this build is called Ghostbusters Engineer. However, this skill is really weak until Tier II when the rockets get the 3 meter burst AoE effect. This is a mid and end game skill, so dont bother putting any points in it until after you have filled several other skills. When this skill finally reaches Tier II the fun really begins. With proper technique you can shoot mobs on clifftops, or across chasms, rivers and bridges. When you have the high ground you can shoot down on your enemies when they are helpless and cant attack you. This is also the best skill to attack mobs that are spread out. If you use this skill without specifically targeting a mob, the rockets seek out the nearest targets in the general direction that you shoot them. With careful aiming you can get the rockets going left and right, or up and down, simultaneously. Use the terrain to your advantage and you will quickly fall in love with this skill.

FIRE AND SPARK
This is more of a late game skill. It compliments Coup de Grace and Fusillade nicely, but thats not the main reason to get 15/15 for this skill. When combined with the unique cannon Old Ironjaw your damage will quickly skyrocket. Even though Old Ironjaw is a level 55 cannon, it's the only one you will ever need for this build even in the end game. The odds are pretty slim that you will find a better cannon with more fire and electric damage than Old Ironjaw.

CHARGE DOMINATION
Most Engineer builds put 1 point into this skill just because it's a nice perk from time to time. Odds are that it will activate about once per horde of mobs even with just 1 point in it. However, in the mid and end game this build NEVER uses basic attacks, hence it doesn't have any means of generating charges except for this skill. In order to maximize the power of Forcefield, a full charge bar is the best option. 12 points in this skill provides an 8.5% chance to activate, which is plenty enough to keep your Forcefield at maximum. Most bosses and hero mobs are accompanied by lesser mobs that you can easily kill in order to activate Charge Domination. This is another end game skill, but go ahead and put 1 point in it early on.


AEGIS - 30

Forcefield - 15/15

Immobilization Copter - 15/15

FORCEFIELD
This is one of the most powerful defensive skills in the game. When combined with a full charge bar, this skill can absorb massive amounts of damage. However, you should ALWAYS have this skill active even if your charge bar is empty because it can still absorb one powerful hit. In the early game you can use basic attacks on trash mobs to fill your charge bar, then activate Forcefield before fighting hero mobs and bosses. In the mid and late game you should keep an eye on your charge bar for when Charge Domination kicks in, then immediately activate Forcefield. If you don't want to die a lot then make a habit of using this skill whenever possible.

IMMOBILIZATION COPTER
Many Engineer builds only put 5 points into this skill, but I think it's worth 15 for a couple of reasons. With 15 points this skill can practically freeze most mobs, and the ability to sometimes interrupt mobs is really powerful in the end game. Be aware that most bosses and some hero mobs are either partially or completely immune to this skill. The electric damage is really insignificant, but it might help finish off trash mobs that are still alive for some weird reason. Sometimes the copter focuses on junk mobs when you are getting attacked by a boss or hero mob that is up in your face. When that happens just recast the copter and it will spawn right next to you.


SKILL PRIORITY

Blast Cannon
Healing Bot
Forcefield

Always keep these skills at maximum until they are 15/15. Eventually you will have some extra points for the next set of skills for this build.


Heavy Lifting
Coup de Grace
Immobilzation Copter

Alternate points between these three skills, but try to get Immobilzation Copter to Tier I before putting too many points into Heavy Lifting or Coup de Grace. I prefer to keep Immobilzation Copter at maximum while I am leveling.


Fusillade
Fire and Spark
Charge Domination

You can put 1 point into Charge Domination in the early game, but the rest of the points should be near the end game. Even when you have a few points in Fusillade it's really not even worth using it until Tier I, but it's much stronger at Tier II. Hopefully you will get Old Ironjaw as a drop about the time you complete your first run through all the acts. If you never find Old Ironjaw, you can always put some fire and electric gems into another cannon or get fire and electric enchantments on a cannon. Even without Old Ironjaw, Fire and Spark will help maximize the damage of Fusillade and Coup de Grace.

Player Spells

For leveling...
Treasure Hunter
Adventuring
Willpower
Armor Expertise


For end game...
Treasure Hunter
Repel
Willpower
Armor Expertise

This build really doesn't need any offensive player spells, but if you prefer you can always add one or two if it's your style. Sometimes it's difficult enough just managing the main skills for this build without adding more to the mix. My experience has been that Willpower and Armor Expertise are must haves for this build. This build doesn't use any escape skills like Tremor or Storm Burst, so the worst thing that can happen is to get frozen, slowed or immoblized. Willpower is a great alternative to escape skills and is really strong in the end game.


Pet Spells
Nether Imps x2
Blood Zombie
Archers

This build doesn't take full advantage of a minion build, but using your pet to summon all these minions lets you concentrate on the action. The minions don't deal any significant damage, but they occupy enemy mobs while you stand back and blast away. If you pay attention you can often use the Archers as a barrier to prevent melee mobs from closing on you too easily.

Gear For Leveling...

When you get to Act II you should buy the pieces for the Ironlord set. When you have the full set the 12% attack speed bonus is awesome with Heavy Lifting. Don't worry if the pieces don't have sockets. Eventually you will meet the socket enchanter and you can take care if it then. I used my Ironlord set from mid 30s level all the way to my early 70s level. With some Vitality gems and Ranged damage gems, the Ironlord set will serve you well.


Gear For End Game...

Eventually you will get to the point that if your Forcefield is down you will die from just one or two hits by a hero mob or boss. The benefits of the Ironlord set are fantastic, but the armor value can't support you into the end game. When you have several Vendor Boon Scrolls, and are at least in the low 70s level, you should try to buy the Labarinto set to take you into the end game. I needed about 8 scrolls to buy 6 Labarinto armor pieces. The final piece is an amulet that you can't buy from the Vendor Boon Scrolls. Hopefully I'll get the amulet as a drop. Make sure you have saved LOTS of gold before using the scrolls.

The Labarinto set has some pretty good benefits although the increased range for Wands, Bows, and Pistols is wasted for this build. However, the Attack Speed, Critical Damage, and Critical Hit bonuses are exactly what this build needs. Additionally, many of the Labarinto armor pieces have a bonus to ranged attack damage. This set will more than double your armor bonus from the Ironlord set.


Cannons...

Almost any cannon will suffice for leveling. But hopefully you will get the Old Ironjaw unique cannon drop around the mid 50s level, or about the time you complete your first run through all three acts. This is the best cannon for this build because it deals a large amount of Fire and Electric damage rather than physical damage. With Old Ironjaw and the Fire and Spark skill, every skill point increases your total damage output by an additional 5%.


Gems

I like to use a mixture of three types of gems to socket my gear. The skulls that increase all damage are great for leveling. Two or three of those skulls makes a big difference. Near the end game I prefer using Orpantile Skulls for the 20% ranged damage boost.

You will need 2 or 3 mana regen gems in order to maintain your mana pool.

To make you less squishy you will need either skulls that increase your health, or skulls that increase your vitality. While leveling I prefer the skulls that increase Vitality, because it also helps increase your armor and resistances. Near the end game I like to add at least a couple of Skulls of Riechliu to push my health up to 10K and higher. You can also sometimes buy these from the Vendor Boon Scroll, but they are incredibly expensive.


Enchantments

I am not too picky about enchantments for armor. While leveling I prefer the enchantments that decrease elemental damage or physical damage. For my cannon I prefer getting 3 fire enchantments.

This is a very fun build to play but it can be challenging while leveling up. In the mid game you have to be very careful. Until you buy your end game armor set you will get more and more squishy as you level up. Be prepared to do some serious kiting in boss fights.

Near the end game this build really begins to shine. After you have Fusillade at Tier I you can just stand back and blast mobs from incredibly long distances. Anything that gets too close gets a dose of Blast Cannon. In the mid and end game I never use basic attacks. I set my normal attack button to Blast Cannon, and my alternate attack button to Fusillade. I keep Forcefield on my switch hotkey so can toggle between Fusillade and Forcefield as necessary.

You MUST use the key to prevent you from moving while attacking. The last thing you want to do with this build is accidentally run into the middle of a mob horde. I use the SHIFT key as my movement stopper keybinding. That way I can line up my left hand on the SHIFT, Z, X, and C keys. I use the C key as my alternate toggle between Fusillade and Forcefield.

You can click on a target then attack it with Fusillade if you want. But most of the time I find it more beneficial to not target anything and just let the rockets fly where they want to go. If you hold down the SHIFT key (or whatever key you use to prevent your character from moving) and place the cursor close to your character, it's very easy to maintain a continuous barrage with Fusillade and rotate your character by carefully moving the cursor in a circular motion around your character. You can rapidly send out a 360 degree spread of rockets if you are getting swarmed and have nowhere to run.

In the endgame every mob is potentially lethal. I like to frequently fire off rockets and gradually move through the map. The rockets show me if there are mobs nearby. Then I just stand back and blast away from a safe distance. When bosses come after me I kite them easily.

This build works just as well on Normal as it does on Veteran or Elite. The only difference is that elite difficulty requires a lot more kiting than veteran or normal.