At first level a Ranger selects a type of creature from the favored enemy list. Favored Enemy grants +2 to damage rolls against the chosen creature type. At 5th level and every 5 levels thereafter (10th, 15th, and 20th) the Ranger selects an additional creature type from the favored enemy list and his damage bonus against all favored enemy types increases by 2.
For example, a Ranger selects Goblinoid as his favored enemy at first level and gets the +2 bonuses listed above. At fifth level, the Ranger is able to select Giant and will get a +4 damage bonus to both Goblinoid and Giant enemies. At tenth level he gets to select yet another class of enemy and the damage bonus on all of them increases to +6.
10/29/17 - The above is somewhat misleading, the original DDO text probably dates back to the days where you could only gain Favored Enemies at specific ranger levels. You get +2 damage vrs each Favored Enemy for each Favored Enemy feat you have, regardless of how you got them. Ranger level is not directly relevant. If I have Undead as a Favored Enemy from the Vistani enhancement tree, and Reptilian from the Gnome Racial enhancement Tree, I do +4 damage to all Favored Enemies. If my lvl 20 ranger has 5 base Favored enemies from ranger Levels, 1 from Deepwood Stalker Enhancments, 1 from Vistani, and 1 from the Primal Avatar tree, I do 16 extra damage.
- Deep Gnome: Goblinoid or Reptilian
- Gnome: Gnoll or Reptilian
- DWS: Animal, Dragon, Dwarf, Elf, Giant, Gnoll, Goblinoid, Halfling, Human, Magical Beast, Monstrous Humanoid, Orc, Plant, Reptilian, or Vermin
- Harper: Aberration / Construct / Dragon / Evil Outsider / Giant / Monstrous Humanoid / Undead
- Primal Avatar: Aberrations / Constructs / Undead
- Vistani Knife Fighter: Undead
- Deepwood Stalker enhancements include effects that increase your defenses and damage versus your favored enemies
Specific exceptions or examples are listed in parenthesis after the race. Click each race (or type) to go to its page, where you can find detailed descriptions and a list of all monsters of that race (or type).
Notes re Ranger's Favored Enemies:
- 1) For Outsiders, a Ranger may select "Chaotic Outsider", "Evil Outsider", and/or "Lawful Outsider" (each separately). The "Race" category of the monster does not distinguish by alignment, so these Favored Enemies tend to overlap some Outsiders and miss others. Mephits are "True Neutral", not Chaotic, Evil or Lawful, and so are not covered by any of a Ranger's possible choices.
- 2) In DnD, "Fey" and "Vermin" are valid selections for a Ranger's Favored Enemy - it is not clear why they are not in DDO (although one could guess that, in the case of "Fey", there simply are not enough representatives to make that worthwhile).
Note also that...
- Humanoid bane covers many of the above types. It is only found on randomly-generated weapons, and is not a possible choice for a Ranger's Favored Enemy.
- Incorporeal creatures fit multiple types above (e.g. Evil Outsider, Undead). Both Lesser and Greater Incorporeal Bane exist in game, on the Phase Hammer, Assassin's Kiss, and Epic Assassin's Kiss and on cannith crafted weapons. Note that Incorporeal Bane does not imply Ghost touch.
- Natural bane, a designation found only on randomly-generated weapons, covers all of Animals, Vermin, Magical Beasts, Plants and Fey.
- Unnatural bane, a designation found only on randomly-generated weapons, covers all of Monstrous Humanoids, Aberrations, and Undead.
- Ooze bane does not make a weapon immune to breakage or splitting.
- Note that several races are listed under multiple types. This is unavoidable, as certain factors cause monsters of the same race to fall under different types. For example, most blue dragons are Dragon type, but Auraxyllon and Eternity are undead, and so fall under the Undead type. The same goes for undead beholders, humans, and rats. Similarly, "Evil Outsiders" may or may not also be "Lawful Outsiders" or "Chaotic Outsiders", and so on.
- Note on choosing a bane weapon: The general rule of thumb is to choose the bane type that corresponds to that particular monster's type, not race. In the example above, Auraxyllon is affected by undead bane, but not by dragon bane, even though it is a blue dragon. Likewise, Death Knights are affected by undead bane, but not human bane. The exception to this rule is that monsters of any of the various outsider types can also be affected by lawful outsider bane or chaotic outsider bane if those monsters are lawful or chaotic, respectively.
For more information on Dungeons & Dragons monsters, you can visit the D20 SRD: Monster page.