We all know of several games where you receive experience points and gain levels. Quite a simple concept: Kill stuff, get stronger. In Warcraft 3, the logic behind gaining experience is, at times, a bit weird. In this article, I'll try to explain some of the principles behind experience points and hero levels.
Before we dwell on the more obscure areas of experience points, let's take a quick look at the concepts the majority is well-aware of.
Experience is shared globally in Warcraft 3. If you have a hero (or several for that matter) that are far away from the unit killed, they'll still gain the experience points. There's an exception to the rule, though. If you have multiple heroes and one of them is within 1200 range of the unit killed while the others are further away, only the hero within the 1200 range will receive experience. The hero will receive the full amount of experience.
To level up your hero, you need to reach a set amount of experience points. With every level, the amount of required experience goes up by 100, starting from 200 to get to level 2. For level 3, you then need 3x100 in addition to what you already have.
Thereby the table of total required experience points is as follows:
Alright, that should make a lot of sense. Now as for gaining these experience points, we have to kill units. The amount of experience points you receive depends on the unit's level. For hero and non-hero units the granted experience looks, respectively, as follows:
The first thing that might be a bit confusing to some is the fact that ALL units have an assigned level. So even though your Footman or Crypt Fiend doesn't have a number above its head like hero units and creeps have, it still has a level that is compatible with the table above.
Luckily there's a quite easy way to determine what level any given unit is. The general rule of thumb is, that the unit's level is equal to the amount of food it costs. There are, however, a few exceptions to this rule like Gryphon Riders who are considered level 5 while only costing 4 food.
It should be noted that even though summoned units also have a set level, they do not give the full experience when killed, as the game uses a "Summoned Unit Constant". This constant is set to 0.50 by default, meaning that summoned units only grant 50% experience.
Now it gets a wee bit weird
Experience from structures
Not only regular units grant you experience points for killing it. Structures that deal damage also have an assigned level that grants experience accordingly. See the table below for the reference of levels.
The only structure that grants experience without dealing direct damage is the Goblin Tinker's Pocket Factory. The Pocket Factory is considered a summoned unit with its levels being 4/5/6, so it'll grant you 42/57/75 experience points for killing it. On a related note: Clockwerk Goblins that are spawned by Pocket Factory are level 0, meaning that they do not grant experience.
High level = less experience from creeping
It's commonly known that you don't get experience for creeping with heroes that are level 5 or above (though they still take a cut from other heroes), but perhaps you never realized that the received experience gradually goes down through level 1-5. This is also why it's better to pick up Tome of Experience after you have finished a creep camp as the experience granted from the tome is a constant amount (100), and thus optimizing the experience granted from the creeps.
While initial experience distribution between two heroes is equal, the actual received amount of points is not equal, due to this reduction. So if you have two heroes, a level 4 hero will soak 50% of the total amount and only make use of 50% of the 50% experience. In other words, they will soak 50% but only make use of 25% of the total amount.
Hex works a bit like this. If you have two heroes in a fight and an enemy Shadow Hunter uses Hex on one of your heroes, said hero will soak up 50% of the experience(from both units and creeps), but it cannot gain any experience.
Another a bit peculiar mechanic is the 'tech bonus'. If you have only one hero unit (including dead heroes and heroes being trained), you'll receive extra experience points if you are either on tier 2 or tier 3. This goes for both creeping and killing enemy units.
If you are on tier 2 you receive a bonus of +15%, while you receive +30% if you are tier 3.
Yes, there's more to gaining experience points than what meets the eyes at first glance, but when you just learned the few different 'mechanics' it not too complex. It's rarely important to know the exact numbers. Just having the rough concepts under your skin is all you will need!