City of Heroes/Enhancements

Enhancements are added to existing powers, making them more powerful. There are several different types of enhancements, but only three real ranks to them (with a few exceptions, i.e. Hamidon enhancements). They come in Training (TO) (usable by any hero), Dual Origin (DO) (usable by heroes of two different origins, e.g. Science and Technology), and Single Origin (SO) (usable only by heroes of one specific origin).

Obtaining enhancements
There are four ways to obtain enhancements. First, it is possible to receive an enhancement from another player. High level players will often give away high level enhancements as they pass through low level zones on their way to a mission. Often these gifts are a reward for a well written bio or a well designed costume. Please don't beg; it only annoys people. You may also receive enhancements as a reward for completing a task force or a story arc. The enhancement will always match your origin, either as a DO or an SO, and you will be able to choose from a limited menu of enhancements. The third, and much more common, method of obtaining enhancements is by defeating villains. Every time you defeat a villain, or are on a team which does, there is a chance that you will receive an enhancement. The enhancement is usually the same level as the villain, give or take one level. You are less likely to receive enhancements from villains who are below your level, and more likely to receive them from villains who are higher than your level. Up through level 14, all enhancement drops will be Training Enhancements. Dual Origin (DO) enhancements begin to appear at level 15, and become more common at higher levels. SO enhancements start to drop around level 22. Even at level 50, you will still sometimes receive a Training Enhancement. Unfortunately, most dropped enhancements will not be useful except to sell for influence. The final method of getting enhancements is to buy them in the stores. Shopping is the only way to guarantee that you receive something you can use.

Villain enhancement drops
All villains will sometimes drop TO enhancements. On rare occasions, just about anybody could drop almost anything. Here are the standard drops for each villain group: 🇨🇴 🇨🇴 🇨🇴
 * Hellion and Skull: Training Enhancements only
 * Clockwork: Tech/Natural DO
 * Vahzilok: Mutant/Science DO
 * Circle of Thorns: Natural/Magic DO, Magic SO
 * Lost:
 * Igneous:
 * Tsoo: Mutant/Magic DO
 * Troll:
 * Outcast:
 * Banished Pantheon: Magic/Natural DO
 * Freakshow: Natural/Tech DO, Tech SO
 * Warriors:
 * Sky Raiders: Tech/Science DO
 * Council: Mutant/Magic DO, Mutant SO
 * Family:
 * Rikti:
 * Devouring Earth: Science/Mutant DO, Science SO
 * Nemesis: Tech/Natural DO, Tech SO
 * Malta:
 * Carnival:

Buying enhancements
You can buy enhancements from your regular contacts, from stores, and from special contacts. At first, you'll probably be shopping with the Freedom Corps Field Trainers, found in Atlas Park, Galaxy City, and a single one in Skyway City. Another option is buying from contacts. The more missions you do for them, the more enhancements they will offer you. There are no stores in King's Row, or any of the Hazard Zones, like Perez Park and the Hollows. Steel Canyon, Skyway City, Talos, and Independence Port have stores where you can buy and sell enhancements. Each store deals with enhancements for one Origin. At higher levels, there are special contacts who will sell enhancements, one contact per origin. You must complete a mission in order to buy enhancements from one of these contacts. For the highest level heroes, there is one contact who sells enhancements for all origins. The easiest way to find the stores and special contacts is to check the maps on VidiotMaps.com.

General info

 * Each power has one enhancement slot to begin with, and can gain more at certain levels, up to a maximum of six. Note that while some powers almost require using all six, some powers would just be wasting slots if you gave them any. For example, do not slot inherent powers (sprint, rest, brawl, etc.). You do not get enough slots to give six to everything.
 * Enhancements are useful over a three-level range, from -3 of your current level to +3. Being sidekicked or exemplared will not change whether or not they work. Green enhancements (+1 to +3) are better than white (+0), which are better than yellow (-1 to -3). Red enhancements do not give any bonuses.
 * Training enhancements can be used by anyone. Double origin enhancements have only two of the five origins that can use it, while single origins can only be used by one of the five. For example, a Mutant can use Mutant SOs, Mutant/Magic DOs, Mutant/Science DOs, and trainings. Trainings are generally used from levels 1–15, DOs from 15–25, and SOs from 25–50.
 * The bonuses given by white (even-level) enhancements are as follows:

Enhancement diversification
Originally, enhancement bonuses simply added on as you added more of them. For example, six white damage SOs would give an ~200% bonus to a power's damage output. Concerned that this was making powers too effective, in Issue 6 of CoH (and at launch of City of Villains) "enhancement diversification" was added. This basically makes enhancements less effective once a certain bonus has been reached. This is generally around six DOs, or three SOs of a single kind. The following chart gives a few modifiers to help show the effects:

Following ED, it is no longer as useful to 6-slot some powers as it once was. For example, the ideal slotting for a basic attack was previously five damage, one accuracy for most powers. Now, 3–4 damage and 2–3 accuracy is more common, or with one slot given to secondary effects of the power, or given to another power entirely. Note that even with ED, some secondary effects are simply not worth slotting, and it's still better to get 2% more damage than, say, 20% more range or 60% more knockback distance.

Combining enhancements
Enhancements can be combined with others of the same kind to produce enhancements of a higher level – this is basically a cost-saving measure to keep your enhancements useful longer, and to allow you to use more of the enhancements you pick up. It is not cost-effective to buy new enhancements simply to combine them with old ones, it is usually better to just live with a level or two of yellowed enhancements and save your influence. Of course, red enhancements need to be combined or replaced as soon as possible.

Enhancements can be combined two times, and each time they go up one level, marked by a "+". For example, a 16++ is the same as an 18. Enhancements that have been combined twice can still be combined into a higher enhancement – for example, the 16++ could be combined with a 19 to create a 19+.

There is a chance the combination will fail, which increases the more different the enhancements are in level. This means you cannot simply buy the cheapest enhancements and combine them with your level 50s, as in the end it will end up costing you more unless you get very lucky. However, if a combination fails, you always keep the higher level of the two.

Enhancements can be combined using one that's been slotted, and one in your 10 inventory spots, or two that have been slotted already into the same power. Trainings and SOs can only be combined with trainings and SOs of the same kind, however DOs can be combined with other DOs as long as they share an origin (and that origin is the one of your character). They still, of course, must be of the same kind (damage and accuracy cannot be combined, for example).

Calculating enhancement bonuses
There are five known types of enhancements in City of Heroes: Training Enhancements (TO), Dual Origin Enhancements (DO), Single Origin Enhancements (SO), Trial Reward Enhancements (TR), and Hamidon Enhancements (HO).

Enhancements are broken down into two categories; range, cone range, defense and damage resist. Enhancements use the lower of the two numbers in the following table; all other enhancements use the higher number.

The level of the enhancement does not directly affect the benefit that enhancement. However, the level of the enhancement relative to the level of the hero does. Enhancements at a higher level than the hero provide a 5% bonus per level difference; those at a lower level have a 10% reduction per level difference. To calculate the value of an enhancement, take its base strength (e.g., 33% for a single-origin damage enhancement), and multiply it by the level modifier (one of .7, .8, .9, 1, 1.05, 1.1, or 1.15).

To calculate the effect of multiple enhancements for a single power, calculate the modifying factor as follows:
 * $$Modifying Factor = 1 + \sum Base Enhancement Strength \times Level Modifier$$

For instance, if a level 32 hero has three single-origin damage enhancements (levels 31, 32 and 35) and one dual-origin damage enhancement (level 33) in one attack, the modifying factor will be:
 * $$1 + .3333\times.9 + .3333\times1 + .3333\times1.15 + .1666\times1.05 = 2.19$$

To see how this affects the power, either multiply or divide the power's basic "value" by the modifying factor (depending on whether the "value" is being increased or decreased). For instance, the above-mentioned hero will be doing 2.19 times as much damage with that attack. Or, if those were endurance reduction enhancements instead, that attack would use this percent of the base endurance:
 * $$1\div2.19 = 46%$$

Note that accuracy enhancements are affected by level difference, but are additive to your base to-hit instead of being multiplied.

Hamidon enhancements

 * Nucleolus: Damage + Accuracy
 * Centriole: Damage + Range
 * Peroxisome: Damage + 'Mez' Effect
 * Endoplasm: Accuracy + 'Mez' Effect
 * Golgi: Healing Rate + Endurance Cost Reduction
 * Ribosome: Resistance + Endurance Cost Reduction
 * Microfilament: Travel Speed + Endurace Cost Reduction
 * Lysosome: To Hit Buff + Defense DeBuff + Accuracy
 * Enzyme: To Hit DeBuff + Defense DeBuff + Endurance Cost Reduction
 * Membrane: To Hit Buff + Defense Buff + Recharge Time Reduction
 * Cytoskeleton: To Hit Buff + Defense Buff + Endurance Cost Reduction