Talented Amplify Magic now provides a substantial boost to healing, but obviously it can increase magic damage taken by a tank as well. I'm curious what the verdict is from various raid leaders on where it's worth using and where it should be avoided. Some fights are worthwhile, others are a little more up in the air. Where do you use Amp Magic?

Yup. That's basically it.

One could argue that even heavy magic dmg isn't an issue. If you're getting hit for 3000 magic dmg every 3 seconds lets say, getting a bit over a 100 more magic dmg isn't going to be a huge deal. Certainly not enough to drop the +225 or so healing you get. 3120 to 3000 isn't much of an issue. Where you wouldn't want to do it is in fights where you're taking lots of continuous magic dmg at low intervals. I'm not sure there are many of them, since I've not raided as far into endgame as many here. Lets say an encounter where you're getting hit by 2 sources of magic dmg every tick for about 150 dmg each. Using amp magic would be very bad there. In the first case above using it would add like 5ish percent more dmg from the magic attack, so it's not bad. In the second case, amp magic would nearly double the dmg you take. Very bad.

I'm not sure if Vael's aura counts as magic dmg, but if it is and the hits are constant enough, that would seem to be a bad place for it. Perhaps Huhuran's poison volly in the last 30% would be a place to not have it on?

Obviously. But that's fairly ambiguous - where do you draw the line? My guess is raid leaders differ in what they consider dangerous to boost with amp magic, thus the reason for this thread. I'm not asking for what SORT of fight, I'm asking which specific bosses you do or don't Amp tanks on. Some are obvious, others much less cut-and-dried.

As already been mentioned, it's a given at any fight without magic damage and if I were the raidleader I´d use it on fights with occasional magic damage aswell. I doubt there's any fight where the extra damage could be that dangerous, let alone exceed the massive healing you gain.

In my experience, raid leaders tend to be very gunshy about things like that. After a wipe, the MT likes to look at his log and find out what killed him. When he sees that that time he just HAPPENED to die because Amplify added just enough to kill him, Amplify is immediately banned forever. They just don't like to take risks. The problem is, of course, that you can't as plainly see when Amplify saves your ass, so the net benefit of using it is overlooked. The same is true for Recklessness in many cases. Sure, it's a bit of extra damage, but it also shortens the fight by a noticeable amount, reducing the chance of death to spike damage by at least as much as it adds.

Anything that casts Shadow Flame would also, probably, be a poor choice for Magic damage. Also, anything that can cast Incinerate/Ignite Flesh, or Blast Wave. Probably anything that casts Conflagration as well.

In other words: BWL probably doesn't work well with Amplify Magic.

Does anyone know how amplify/dampen actually works with npc casted spells?

We did some pvp tests with dampen a couple days ago and found out it really doesn't work the way you'd think -- or it does if you think of it like another focus effect. The +heal on amplify definitely scales based on casting time (much like bolight.. in response to the mass spam folr2 tactic), and the -dmg on dampen spreads the dmg across dot ticks (ie it removes a whopping -7 dmg per serpent sting tick or something).

Which of course immediately begs the question, how does amplify work exactly on npc casted dots (and ae's in generall... does it get scaled down based on casting time when most npc spells are instant?) , and does dampen work the same way on npc dots that it does on pc dots?

It kind of matters a lot, because no one cares about +135dmg over 8 seconds from acid spit, but we sure do care about +135dmg every second for 8 seconds.

Why not use both? It depends on how much attention youre willing to focus on it and if its a fight where mages would be aggro-limited and thus have the mana to blow on it or not, but you could amp the tank and have him click it off when shadowflame begins to cast for a boss like ebon, properly tranqd flamegor, and nef. If there was mana to spare, mage could even cast dampen to remove the amp, and back to amp after shadowflame landed and the tank wouldnt have to do anything.

In my experience, Amplify/Dampen gives the full bonus to NPC spells. I haven't checked to see if it is spread out over the length of a DoT or not, but for auras or single hit spells, it's full bonus.

theres really little fights where it isnt many many times better than not putting it
vael, firemaw, rag for example are fights where i use danpem magic on pretty much everyone since its mostly magical auras that do dmg
on like all the other fights its amplify magic, at least on the MT/OT... whats +150dmg to a shadow flame when the tanks get multiple heals per second ?