Bleed, Poison, Maim, Intimidate - how does it work?

Okay, let's talk about the status effects first: Intimidate, Maim, and Hinder. Importantly, these are not considered ailments, so anything that benefits ailments won't work with them.

Intimidate simply makes the affected enemy take 10% increased damage from all attacks.

Maim and Hinder are similar: they both reduce the affected enemy's movement speed. Maim is a flat 30% reduction, the reduction from Hinder varies depending on the source. The important distinction is that Maim can only be applied by attacks, and Hinder only by spells. Even if something would suggest otherwise, that is always the case. (If something says "X% chance to Maim on Hit, it still only applies to hits with attacks, not to spell hits.)

Your character does not start with any innate chance to Intimidate, Maim, or Hinder. It has to come from items, skills, or the passive tree. The sources of each are listed in the respective wiki pages linked above. The chance to inflict the status ailment from all sources is simply added up, and then each of your hits that fulfills the requirements has that big of a chance to inflict the status condition on the target.

Example: You are wielding a Taproot with 20% chance to Maim and you are an Assassin with the Noxious Strike ascendancy passive with 50% chance to Maim Poisoned enemies. If you hit an enemy that is not Poisoned, only the 20% chance from Taproot applies. If you hit a Poisoned enemy, there is a 70% chance you will Maim them instead as both sources are added together.

All three status effects are binary, an enemy either is Maimed or it is not. Two of the same effects don't stack, only the most powerful one applies. However since Maim and Hinder are two different effects, an enemy can be affected by both at the same time.

I don't believe players can be Intimidated, Maimed, or Hindered in any way (other than in PvP), so there is no need to defend against these conditions.



Now to Poison and Bleeding. These are considered Ailments, and thus will benefit from any ailment modifiers (such as the common "increased damage with ailments" from the skill tree).

Both of these work in a similar way. If an enemy is hit, it will start taking a portion of the incoming damage of certain types as damage over time for some period. Note that only the base damage of the hit contributes to the amount of Poison/Bleeding damage, before any modifiers. This is why most sources of increased attack damage also modify the damage of ailments at the same time. (This change was made some time ago to prevent so-called "double-dipping".)

The base damage of Poison is 20% of the combined Physical and Chaos damage of the hit inflicting the Poison per second, for 2 seconds (by default). Poison deals Chaos damage. Multiple instances of Poison on the same enemy stack and all deal damage at the same time. Therefore Poison is useful for scaling attacks which deal a large number of hits quickly.

The base damage of Bleeding is 70% of the Physical damage dealt by the attack per second (up to 140% if the target is moving!) over a period of 5 seconds. Bleeding deals Physical damage. Unlike Poison, a target can only take Bleeding damage from one source at the same time. All instances of Bleeding affecting a target are tracked by the game, but only the most powerful one actually deals damage to the enemy. Thus Bleeding is useful for builds which deal singular big, slow hits. (Note that this restriction can be lifted by the Crimson Dance passive, which allows a target to have up to 8 active instances of Bleeding to deal damage to it at the same time!)

As with the above status effects, by default your character does not start with any chance to inflict Bleeding or Poison. The chance has to come from skill gems, items, or passive skills. And again, all applicable sources of chance to Bleed/Poison are simply added up together, and every one of your hits will have that much chance to cause Bleeding or Poison.

Note that unlike elemental status ailments (Chill, Freeze, Shock, Ignite), critical strikes do not have any implicit chance to cause Bleeding or Poison.

Also note that having over 100% chance to cause any ailment or status effect is functionally equivalent to a 100% chance. You will not, for example, inflict two stacks of Bleeding with a single hit if you have 200% chance to cause Bleeding.

Many monsters can cause Bleeding or Poison. Since Bleeding deals Physical damage and Poison deals Chaos damage, anything that reduces that type of damage will also reduce the damage of these ailments. (Note that Armor does not reduce Bleeding damage, since Armor only works against hits, not with damage over time.) For some examples, Endurance Charges give you additional Physical damage reduction; and Chaos resistance is commonly found on gear. Since the damage of Bleeding is higher when you are moving, stopping your character in place while the Bleeding wears off can significantly reduce the damage received.

In addition to that, there are flask modifiers which make you completely immune to Bleeding (of Staunching) and Poison (of Curing) for their duration. Using one of these flasks also removes any instances of Bleeding or Poison currently active on you. This is the most effective way of countering damage from these ailments.