Deathknights:
Blood - Each time you heal with your Death-Strike Ability you gain 50+x% of the heal as an absortion shield
This is clearly a lovely mastery for blood dk tanks, as of now they (and druids) would be very much sponge tanks without this sort of mechanic either through talents or this mastery bonus. I personally like the feel of this mastery, it feels very akin to blood and well ye it feels like a lovely tanking bonus
Frost - Increases Frost Damage done by 20+x%.
I feel like this is a really lacklustre mastery, it doesn't really have a cool gimic or change the way the class behaves and is just basically +20% damage you gain at lvl 75, which doesnt sound fun to me at least. I personally feel like if they tied it into weapon damage and make it feel dual wield-esque that it would be much more awesome.
Unholy - Increases damage done by your diseases by 20+x%
This is a little better than the frost mastery, it at least makes diseases much more important and may change gameplay somewhat, it also feels unholy, although I feel like an increase to pet (ghoul+gargoyle) should also be baked into the mastery to feel completely unholy-esque.
Druids:
Balance: Increases the Bonus Damage from Eclipse by 12+x%
Definitely a good mastery, makes proccing eclipse that much more needed when levelling as well as the new eclipse mechanic just being plain cool.
Feral : Increases damage absorbed by Savage Defense by 32+x% and increases your cat-form bleeds by 20+x%
Another good solid mastery that enhances the essence of cat damage, same with the bear mastery with a similar description to the blood mastery behind why this is good.
Resto: Increases Healing from hots by (20+x)*y%, where y is a number based on how much hp the target has, (y gets bigger the lower hp the target has).
This is a lovely healing mastery, it obviously brings out the strength and say "perk" of being a druid healer and also gives them new mechanics that they are more powerful the lower the targets are, overall a very nice mastery.
Hunters:
Beastmaster: Increases damage done by pets by 20+x%
Again, rather generic mastery but overall expected, perhaps I would like to see another go for the throat type mastery thrown in there like your pets also gain a 10% chance to gain 20+x focus on a hit, or something like that. I don't play a hunter but I think that would be cool
Marksman: Grants a 16+x% chance on ranged attack to automatically fire a shot that hits for 80% of a normal attack.
Again, nice mastery, obviously en-corperating wild quiver into this talent but it does get across what marksmanship is all about in my opinion so it is a good mastery.
Survival: Increases Elemental damage by 20%.
Personally I think this is a good/bad mastery, although this is more to do with survival playstyle than the mastery itself, this is a good mastery for the spec (although boring) but I feel like survival should be about tracking and traps more than about shots than it is today, it would be awesome to see a spec that was all about trap launcher and traps especially, I know black arrow is meant to facilitate this but with the introduction of trap launcher i feel like that should become a signature ability of the survival hunter.
Mage:
Arcane: Increases the amount of damage done by the mage by (12+x)*y% with y based on how much mana the mage has unspent.
Whilst I actually love this talent and it feels very arcaney to have to manage mana within your spec, not to go oom but to maximise damage, I just feel its going to be hard to balance unless it has a minimum point like, say once you get to around 60% mana it always does 6+x% damage or something, so that stuff like Evocation and Mana gem give you significant damage boosts but you can balance the mage about having this consistent damage buff up say 70% or whatever it works out to be time.
Fire: Causes your non periodic Spells to do 10+x% extra damage over 4 seconds.
Again this is just Ignite, but it's a cool way to basically add 10% extra damage to a class, even if it will always work out less than that unless it ends up double dipping on encounters like Blood Queen lanathel etc.
Frost: Causes victims of your Frostbolt to take 12+x% increased damage from your spells
Again another unique way to staple frostbolt as a signature move and to just add damage % to a class, I don't know if this has a timer or not on live not sure if it needs one or not.
Paladin:
Holy: Causes your heals to place a shield on the target absorbing 8+x% of the amount healed
Personally, I love this mastery, it's great to see valanyr encorperated into a Holy Paladin, I always felt that having only 1 class bring definitive absorbs is too much of an imbalance to balance, but having a Paladin have a reliable absorb aswell as this mastery means that Holy Paladins have a good damage reduction. I always felt shamans would get this sort of mastery over a Holy Paladin, but I do like this mastery alot.
Protection: Increases your chance to block melee attacks by 16+x%
A bit generic, I always saw that with wrath you wanted to make like Druids the BIG ARMOR TANK, Warriors the block less but block for more tank and Paladins the BLOCK ALOT but for less tank, this sort of confirms that. Bit torn on how I feel about it, 16% seems quite a large baseline amount though tbh.
Ret: Increases all Holy Damage Done by 20+x%
Again, really generic and imo doesn't get what the Retribution Paladin class is about, I personally feel it should be your Judgement increases holy damage done by 20+x% since thats the staple move of the retribution paladin imo, but yeh not exactly game or decision changing. Although I DO NOT LIKE how a paladin without this mastery and zealotry is losing 40% of their damage until they get it.
Priest:
Discipline: Increases the potency of your absorption spells by 20+x%
Nice healing mastery, Definitely encompasses what the discipline class is about and well yeh theres not much more to say about it, good generic mastery
Holy: Your Direct healing spells also heal the target for 10+x% over 6 seconds
Again a nice mastery, fits in with the healing class and is a much nicer way of showing the player 10% extra healing, it also gives priests more arsenal than just renew as a hot.
Shadow: You have a 10% chance for SW;P and Mind Flay to Grant a Shadow Orb, which increases the damage of Mind Blast and Mind Spike by 20+x%
Personally I feel like there should be more of these type of masteries, stuff that are really integral to the playstyle of the class and are fun, diversifying the classes more than they are today. This mastery is one of the best on the beta tbh and I hope some of the +20% generic masteries get reworked to something like this.
Rogue:
Assasination: Increases your poison damage by 20+x%
Nice mastery, outlines that assasination is about poisons and ye is just a good mastery, bit generic but good.
Combat: Your Main hand attacks have a 10+x% chance to trigger an extra off-hand attack
Again, nice mastery fits in well with the rogue class and with the combat spec in general
Subtlety: Increases the damage of your finishing moves by 20+x%
Staples subtlety as the spec that has the high finishing moves, which is definitely a good thing, considering hardly anybody plays subtlety at the moment, having it become the spec which hits the hardest is only a good thing.
Shaman:
Elemental: Grants a 20+x% chance for your Lightning Bolt/Lava Burst/Chain Lightning to send out a second similar spell causing 60% of the damage.
Very nice mastery, sure it's just a remake of elemental overload but that talent was awesome and having it become a mastery is definitely a great thing.
Enhancement: Increases your elemental damage by 20+x%.
Again, really generic I'd personally like something that staples Dual Wield with the mastery rather than just a generic +DAMAGE modifier.
Restoration: Increases your direct healing spells by (20+x)*y%
Similar mastery to the resto druid, but tbh they are good masteries that affect gameplay somewhat and it gets across that shaman are somewhat masters of direct healing, which is good.
Warlock:
Affliction: Increases all periodic shadow damage by 13+x%
Good generic Mastery, gets across that affliction is all about periodic damage, as an aside to this, I would like some way for dots to be more effective when questing at low level at least, they always seem far too wasteful and mana burning, a way of transferring dots to another target like rogues were/are getting for combo points would be really nice.
Demonology: Increases damage done by your demon and in Metamorphisis by 12+x%.
Excellent generic Mastery again.. not much to be said other than I wish we had more shadow priest esque masteries :).
Destruction: Increases fire damage you deal by 10+x%
More boring generic mastery but I suppose its good for its purpose
Warrior:
Arms: Grants a 16+x% to your melee attacks to trigger an extra melee attack for 50% of the damage.
Awesome Mastery, a little repeated across the classes but it definitely suits all the classes it was given to and especially arms, also nice for the old sword spec to get a return, hopefully this doesnt get a massive internal cooldown D:.
Fury: Improves abilities that cause you or require you to be enraged by 80+x%.
Really awesome mastery: gets across what the fury spec is all about being like RAWR DAMAGE!!?!?!?!, also like how it will benefit stuff like blood craze and frenzied regeneration aswell, which is kinda sweet
Protection: Increases your chance to block and to critically block by 10+x%
I feel like Critical block should be the mastery on it's Own, although I believe thats bad wording of the mastery and actually you only can critically block with the mastery, which is much nicer tbh. A good mastery if critical block is only available with it, otherwise dull and generic.
Overall I think there are far too many generic masteries at the moment, personally I don't like seeing those pure +% things, they are dull and I feel like, well if everything is meant to do +20% damage or w/e anyway why not just bake it into the talents instead of making a level 75 20% MORE POWERFUL than a level 74, obviously the less generic talents may have a similar effect but its a more fun way, something that staples the rotation or SIGNATURE MOVE of the class should really be the mastery
I do have to say that all the healing masteries are good, I don't mind that some are a little generic they are functional and healers should have more PROCY/FUN masteries that provide rng to healing, there isn't a place for that in healing in my opinion.