Upcoming changes to Leech

We, like many gamers, love life leech mechanics. The idea of turning an offensive attack into a defensive form of survivability, by absorbing some measure of that damage as life, is both thematically interesting and adds depth to character and gear choices. But leech has always posed some balance problems.

When we changed the leech system in Sacrifice of the Vaal, we fixed some exploitative problems, but introduced new ones. With an upcoming change to leech, we intend to readdress both the old issues of leech and issues the previous iteration of leech introduced.

The changes we will be making to leech, for testing on Beta will be:
Multiple leech effects will now stack (ie. a single hit against multiple targets will grant multiple effects, as will multiple hits against a single target).
Base leech rate will be substantially reduced for both life and mana, with less of a reduction to mana leech rate, bringing it in-line with life leech rate.
A maximum leech rate will cap the rate at which you can leech.
Methods of improving leech, leech rate and increasing your maximum leech rate will be added to new clusters in the passive tree, primarily in the regions between the Marauder, Duelist and Ranger sections.
Some of the already existing clusters in this region that specialized in specific weapon types will also have leech elements added to them.
All existing values of leech will be substantially reduced, including values on existing items.
Vaal Pact will be adjusted to account for the new values of leech.

The goal is to have leech be as effective as it is on the live servers, if not better, against packs of monsters, while being more difficult to get to the same levels of survivability and sustainability against single powerful monsters such as strong rares or bosses.

Players who specialise in leech (allocating the passives related to improving it) would be substantially better at leeching than they currently are on the live servers against packs of monsters. Leech is not intended to trivialise bosses.

We want the Duelist to receive the most love from these leech passive tree changes, in order to add some flavour, power and more choice to his tree. They will also benefit anyone travelling to that part of the tree.

While most of these changes are focused towards life leech, mana leech is also being altered. The base maximum mana leech rate will be higher than the current rate on the live server, and opportunities to invest and increase the leech rate further will be available.

We're excited to see what players do with these changes in the beta, and will endeavour to keep players up-to-date with any further changes we make to the system.

Update:

Due to the changes to leech, one of the compromises we've had to make is that leech will be far less effective early to mid game.
Because of this we have adjusted the levels of the mods for Life Leech on items, these changes will not affect the level requirements on existing items.

The new item levels required for Life Leech Mods are:

Remora's (50)
Lamprey's (60)
Vampire's (70)

And for Mana Leech Mods:

Thirsty (50)
Parched (70)

Corruption Mods for Elemental Life Leech on Amulets now require item level 50.

Vaal Pact no longer penalizes the amount of life Leeched, it will now apply 100% of life leeched instantly, while still not allowing Life Regeneration.

Vaal Pact has also been moved to between the Shadow and Ranger on the passive tree.

All the existing cases of leech on items is now 20% of what it was before, for example an item with 1% Life Leech, will now have 0.2% Life Leech. This has been applied to all existing items.

Some things such as the Support Gems and Warlord's Mark have had their values reduced by 80% and then manually adjusted. The Life and Mana Leech support gems no longer increase in the amount leeched per level, this is because with the new values at 20% of the original values they were very ineffective at level 31, so they now start much higher and only the rate of the leech will increase as they increase in levels.

The new Base Values regarding Leech:

Base Maximum Life Leech Rate is 20% of maximum life per second.
Base Maximum Mana Leech Rate is 20% of maximum mana per second.
Base Life Leech Rate is 2% of maximum life per second.
Base Mana Leech Rate is 2% of maximum mana per second.

Update 2:

Taken from the State of Beta #8, Here are the latest changes to Leech:

We have worked out we need to change leech rate as it currently works. Currently, when you would already be at the Leech Cap, the rate increase does not give you more leech, as you are already at the cap, while it still reduces the time taken to leech. This can make Leech Rate detrimental to a player in fights against large number of targets, or who otherwise reaches the leech cap quickly.

We will be changing increased Leech Rate to increased Life/Mana Leeched per Second. This will be best against single targets, or in times when you do not reach the Leech Cap, but will not be detrimental in situations you are against a large number of targets.

We are also looking at increasing the values of the Leech Cap. We will then have two main bonuses affecting leech gained, with Leech Cap bonuses best against packs, and Increased Leech Per Second bonuses best against bosses. Neither will be detrimental to the player.

Energy Shield Leech was also bugged on the beta, and was not stacking in the way Life and Mana Leech now are. This will be fixed on the next deploy.

Further explanation of the changes from Leech Rate to Increased Leech per Second:

Previously, we had modifiers for "increased (or reduced) Life/Mana Leech rate". These did two things:
They increased value of Life/Mana you're gaining per second for each leech effect.
They reduced the duration of each leech effect, such that the total life/mana gained over the duration remained the same.

All such modifiers have now been changed to "increased (or reduced) Life/Mana Leeched per second". This still increases the value of Life/Mana you're gaining per second for each leech effect, exactly as it did before. It no longer affects duration of the leech effects, meaning you'll gain more total life/mana from each one as a result.