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### Path of Exile Mana Regeneration Guide

Path of Exile Mana Regeneration Guide by RulerofAsgard

The following post is an exhaustive breakdown on Mana Regeneration and why it is useful for builds that depend upon casting several spells per second – my example will be my current Hardcore character, who is a Fire Summoner Witch in Cruel Act 2.

This is my current build:

This is my intended build 2 levels from now:

Some important information about my character:

Base Mana: 511
Mana Regeneration from gear: 41%
Mana Regeneration from passives: 60%
MR from passives in 2 levels: 100%
Mana per second from Clarity: 11.9
Inner Force buff to Clarity: 30%

Fireball base casting Cost: 22
Greater Multiple Projectiles: 200%
Faster Casting: 120%

Base cast speed of Fireball: .85
Faster Casting increased cast speed: 22%
Increased cast speed from gear: 10%
Increased cast speed from passives: 10%

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The basic formula for calculating Mana Regeneration per second is this:

((Base Mana * 1.05)/60) * (1 + MR from gear + MR from passives)

With Clarity and Inner Force, it becomes a little more complex:

(((Base Mana * 1.05)/60) + (Clarity’s Mana/sec * (1 + Inner Force bonus))) * (1 + MR from gear + MR from passives)

Using the numbers I gave for my character, my Mana Regeneration per second is:

(((511 * 1.05)/60) + (11.9 * (1+.3))) * (1 + .41 + .6) = 49.069125 = ~49.1

My tooltip for Mana Regeneration per second shows 49.1, so we are good so far.

Using the numbers I provided for 2 levels from now, I get:
(((511 * 1.05)/60) + (11.9 * (1+.3))) * (1 + .41 + 1) = 58.834125 = ~58.8

So as this shows, two “20% Increased Mana Regeneration Rate” nodes equates to 9.7 higher Mana Regeneration per second – an increase of nearly 20% total regeneration in my case.

----------------------------Why is this important, you may ask?----------------------------

Take a look at Fireball. Currently, it is linked with GMP and Faster Casting. This means the cost per cast is:

22 * 2 * 1.2 = 52.8 = ~53 (tooltip shows 53)

Now we must calculate the number of casts per second, which is done thusly:

(1/Base Cast Speed) * (1 + Faster Casting bonus + Gear bonus + Passive bonus)

So for my numbers this is:

(1/.85) * (1 + .22 + .1 + .1) = 1.670588 casts per second (tooltip shows 1.67)

Using this, the total cost per second to cast Fireball is:

52.8 * 1.670588 = 88.20706 = ~88.2

My total usable Mana pool is:

Base Mana – Reserved Mana = 511 – 260 = 251

This means I can cast Fireball:

251 / 88.2 = 2.845… times WITHOUT Mana Regeneration.

With the Mana Regeneration I currently have (49.1/sec) I can cast Fireball:

251 / (88.2 – 49.1) = 6.42 times

Two levels from now, I will be able to cast Fireball:

251 / (88.2 – 58.8) = 8.54 times

This means that I can cast Fireball 2 additional times before needing to pop a Mana Flask or needing to stop casting to allow my Mana to regenerate, which equates to a 33% increase in DPS.

If you find any errors in the above, or if you have any questions, please feel free to point them out/ ask away, information is a powerful tool, so it is key to make sure what you know is accurate.

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