When I mouse over the buff, it says 15% HP and 30% healing glyphed.

I was testing the 4pc myself and got similar results where it seemed to be above 15%, but less than 30%. Something of interest is that a quick search through wowhead brings up some good points.

Here is Frenzied Regeneration: Frenzied Regeneration - Spell - World of Warcraft (click to see values). Notice the "max health" value is set at 30.

Here is Mass Regeneration(the raid buff): Mass Regeneration - Spell - World of Warcraft (click to see values). The "max health" value is set at 15.

I tested it both unglyphed and glyphed and the hp bonus was the same amount. Will be nice next week when more people have the 4pc to mess around with.

I am going to do some more testing during our raid on Sunday to see if I can nail down the exact amount it's currently giving.

Did some testing with the unglyphed version of the 4pc tonight in DS/Firelands. It actually is kind of a lot of HPS (bursting up to 45k+ in Firelands). During Madness of Deathwing one use at the correct time yielded around ~6.7million of raid healing, with a very low margin of overhealing ~5-6%. There could be some situations where it's more useful than the glyphed version. Also, if you are still doing Baelroc and get HP stacks, use your 4pc for the most ungodly HPS you'll ever see.

This is just me for the stat priority, I reforge to ensure get as close to hit/exp cap (hell even used agi/hit gems if i like the socket bonus) then the rest dodge. Mastery is a good stat but with some of the fights and 2 tanking mastery still does not weigh up as much as dodge. I am a firm believer in mastery has lower priority if you dont have hit/exp cap'd cause there will be no SD proc if you miss or get parried/dodged. I do focus on reforging to hit/exp since the DR I currently have on dodge is just retarded and I know as I move from H FL to DS gear it will be even worse.

I do have a question about armor though, is there a cap on it at 75% reduction or did i miss read that? If there is by chance does anyone have the actual number that is so I can ensure i dont pass it.

My Druid is Archangelass on Dalaran.

Could the shaman healing buff possibly be the culprit on the confusion? Not certain as I don't have 4 piece yet but it could throw the % off a bit giving the timing of the buff being up or down on certain players.

So if you had ~210k health buffed, that would be ~230k with ancestral healing and ~300k with frenzied regeneration. Thus frenzied regeneration would heal for 9k health per second per player; across 25 players that's 225k health per second.

In order for the 30% healing from the glyph to be better, the healers would need to be doing more than 225k/.3 = 750k healing per second, which is 2-4 times typical burst healing values. Therefore, in almost no cases is the glyph worthwhile. You would use the glyph if only a small fraction of the raid needs healing when you use frenzied regeneration.

Also, if you could use frenzied regeneration on cooldown without overheal it would average 225k/9 = 25k hps over the fight. On Ultraxion it would average 100k hps over the fight.

I was thinking about trinkets last night and here's what I plan to be using: Any other suggestions or ideas would be appreciated.
Morchok: Wrath of Unchaining (Stacking Agi), Resolve of Undying (Stacking Dodge)
Damage incoming is pretty much all physical, with effects that increase damage taken, further boosting agi/dodge over stam or mastery.

Yorshaj: Wrath, Mirror
Good old mirror comes back again, on a fight where 75%+ of the damage you take is magic, its a no-brainer.

Zon'ozz: Wrath, Mirror
His beam does a lot of damage as a huge spike so probably mirror again.

Hagara: Wrath, Matrix
Even on heroic tank damage was very low on the PTR so dodge wouldn't be as good. Not enough unavoidable magic damage to need mirror. Lots of time off the boss means stacking trinkets will probably fall, and will give plenty of time for Matrix to come back off CD.

Ultraxion: Wrath, Indomitable Pride (Stam, Shield Proc)
A close call, but for now I'm going to use Indomitable both because Ultraxion can melee pretty hard in the window between CDs, and to have more health for Hour. Resolve could definitely be used here though.

Blackhorn: Wrath, Resolve
Huge tank damage in a short amount of time rules out Indomitable proc, and any increase to the chance to dodge sunder help a lot.

Spine: Wrath, Indomitable Pride (Amalgamation tank) or Matrix (Blood tank)
Infrequent periods of very high mob damage is perfect for Pride. If your on bloods you probably just want to maximize the damage you can do to the tendons.

Madness: Wrath, Matrix
We spend about 75% of the fight in cat so you want Agi trinkets. Magic damage is too constant for mirror to help much, and Pride won't help with Impales.

Trinket Subsitions.
I'm assuming every has mirror/seed and some kind of matrix by this point.
Morchok: Matrix is always a good on a physical fight. Seed/Fire from the Deep are still good, but their mastery is devalued by fight mechanics. Their uses can be nice if by luck you get to 3-4 stacks of sunder (Normal) or get hit by the other tank's stomp (Heroic). I would still avoid stamina trinkets since the damage is not spiky or huge until the final burn which you'll have majors for.
Yorshaj: Magic damage is really the only part to tank damage on this fight so your other trinket doesn't matter, I would use matrix. I might also try Sindragosa's Fang.
Zon'ozz: Matrix or Seed/Fire. Matrix gives more overall, but Seed/Fire will let you use your trinket proc when he has many stacks.
Hagara: Still not enough magic damage to justify mirror, so Seed/Fire
Ultraxion: Matrix or Seed to boost your cat time. Once we get better gear probably Matrix over Pride anyway.
Blackhorn: Seed/Fire, you really really need to dodge those sunders if you can.
Spine: Seed or maybe even Spindle for when the Amalgamation starts hitting hard.
Madness: Seed or maybe even a DPS trinket with passive agility.

That is a post that needs to be bookmarked, tremendous list!!

I was speaking with a friend of mine and he was planning on trying the Bedrock Talisman tonight on heroic Morchok, he claimed that it would be a viable choice for that fight, I'm not 100% on that but if it works out for him I'l definitely edit this post. Regardless, it will be interesting to see some damage/mitigation numbers later on in the week once more bears get a chance to tank the heroics.

Thanks again for the list by the way.

Actually in my recent experience on Heroic Morchok it'd be best to combine Wrath/Indomitable. Wrath obviously plus the 2pc provide physical mitigation but Indomitable will proc on every stomp, every 1min, giving your healers time to catch up.

On a side note, I used to stack agil but I switched to stam gems, a healthy mix with the offsetting values provided by switching trinkets has proved best for me so far. Between the kiril Polearm: Kiril, Fury of Beasts - Item - World of Warcraft and wrath you should have enough agil to add in a healthy mix of stamina, except for the fights where we'll be dpsing 75% of the time.

Yes, our bear was healing us for roughly 4,5k per tick with about 300k health during Frenzied Regen. This matches the max health buff of 15% which the raid receives instead of 30%, as both seem to have an reduced effect of 50%.

Currently our bear is stacking Agi, but with unglyphed 4pc, stacking Stamina might be a better choice, also considering the amount of spell damage from bosses this tier.