Season 3 Mastery Changes With Details & Stats

From left to right and from top to bottom.

OFFENSE

Tier 1

Summoner's Wrath :
Exhaust : Reduces target's MR and Armor by 10
Ignite : Increases AP and AD by 5 while on CD
Ghost : Increases MS bonus to 35%

Fury : +1% AS/+2% AS/+3% AS/+4% AS
Sorcery : +1% CRD/+2% CRD/+3% CRD/+4% CRD
Butcher : Basic Attacks deal 2 Bonus Damage to minions and monsters / 4

Teir 2 :

Deadliness : +3 AD at level 18 (0.17/level)/+6 (0.33/level)/+9 (0.5/level)/+12 (0.67/level)
Blast : +4.5 (0.25/lvl)/+9(0.5/lvl)/+13.5 (0.75/lvl)/+18 (1/lvl)
Destruction : Increases damage to turrets by 2.5%/Increases damage to turrets by 5%

Tier 3 :

Havoc : Increases damage by 0.67%/1.33%/2%
Weapon Expertise : +8% Armor Pen
Arcane Knowledge : +8% Magic Pen

Tier 4 :

Lethality : +2.5% Critical Strike Damage (+5% for melee champions)/ +5% (+10% for melee)
Brute Force : +1.5AD/+3AD
Mental Force : +1.5AP/+3AP/+4.5AP/+6AP
Spellsword : Deals 5% of your AP in magic damage to the target on each basic attack

Tier 5 :

Frenzy : Gain 10% AS for 2 seconds after landing a critical hit
Sunder : +2 Armor Pen/+3.5/+5
Archmage : Increases AP by 1.25%/2.5%/3.75%/5%

Tier 6 :

Executioner : Increases damage dealt by 5% to targets below 50% Health

DEFENSE

Tier 1 :

Summoner's Resolve :
Cleanse : Increases duration of disable reduction by 1s
Heal : passivley increases health by 5/lvl
Smite : Grants 10 bonus gold on use
Barrier : Increases shield amount by 20

Perseverance : Grants up to 2+ Health Regen/5 based on missing health. /4/6
Durability : +27 Health at level 18 (1.5 Health/lvl) / +54 (3/lvl) / +81 (3/lvl) / +108 (6/lvl)
Tough Skin : Reduces damage taken from monsters by 1 / 2

Tier 2 :

Hardiness : +2 Armor / +3.5 / +5
Resistance : +2 MR / +3.5 / +5
Bladed Armor : Deals 6 damage to any enemy monster that attacks you

Tier 3 :

Unyeilding : Reduces damage taken from champions by 1 / 2
Relentless : Reduces the efficness of slows by 7.5% / 15%
Veteran's Scars : +30 Health
Safeguard : Reduces damage taken from turrets by 5%

Tier 4 :

Block : Reduces damage taken from champion basic attacks by 3
Renacious : Reduces CC by 5% (stacks mutiplicatvely with Tenacity)/10%/15%
Juggenaut : Increases your maximum Health by 1.5%/2.75%/4%

Tier 5 :

Defender : Grants 1 Armor and 1 MR for each nearby enemy champion
Legendary Armor : Increases bonus Armor and MR by 1.25%/2.5%/3.75%/5%
Good Hands : Reduces time spent dead by 10%
Reinforced Armor : Reduces damage taken from critical stikes by 5%/10%

Tier 6 :

Honor Gard : Reduces damage taken from all sources by 3%

UTILITY

Tier 1 :

Summoner's Insight :
Revive : rants bonus health for 2 minutes upon reviving
Teleport : Reduces cast time by 0.5s
Flsh : Reduces theCD by 15s
Clarity : Increases mana restored by 25%
Clairvoyance : Grants additional vision of enemy champions revealed

Wanderer : Grants 0.66% increases MS when out of combat /1.33%/2%
Meditation : +1 Mana Regen per 5s /2/3
Improved Recall : Reduces the cast time of Recall by 1s, and Enchanted Recall by 0.5s

Tier 2 :

Scout : Wards gain 25% increases vision for the first 3s after placing them
Mastermind : Reduces the CD of summoner Spells by 4%/7%/10%
Expanded Mind : +72 Mana at level 18 (4/lvl) / +126 Mana (7/lvl) / +180 (10/lvl)
Artificer : Reduces the CD of activated items by 7.5%/15%

Tier 3 :

Greed : Grants an additional 0.5g/10s/ (1g/10s) / (1.5g/10s) / (2g/10s)
Runif Affinity : Increases buff duration by 20%
Strenght of Spirit : Grants up to 1+ Health Regen/5s for each 400 mana you possess / (+2 Health Regen/5s) / (+3 Health Regen/5s)
Biscuiteer : Start the game with a regnerative biscuit that restores 80 health and 50 mana over 10s

Tier 4 :

Wealth : Increases starting gold by 25/50
Awarness : Increases EXP earned by 1.5%/2.5%/3.75%/5%
Vampirism : +1% Lifesteal AND Spell Vamp / +2% / +3%
Explorer : On Summoners Rift, grants a ward at the start of the game that can be placed to reveal the surrounding area for 60s. On all over maps, grants 25 starting gold.

Tier 5 :

Pickpocket : Grants 5 gold for melee hampions and 3 gold for ranged hampions each time you perform a basic attack against an enemy champion (5s Cooldown)
Intelligence : +2% CRD/ +4% / +6%

Tier 6 :

Nimble : Grants 3% increases MS

Huge thanks to TwistedKeyblade

Source: http://na.leagueoflegends.com/board/showthread.php?t=2805186