I've seen this come up a lot lately, usually in response to trying to figure out what to do with death knights during the Lady Deathwhisper fight, and so I thought maybe it'd be helpful (following up on my resolution to be more useful) to provide a guide to which of our powers do magic damage and which ones are all physical. Yes, much like enhancement shamans, we're a delightful mix of both. The ratio of physical to magical varies by spec, though, as you'll see.
What does this really mean, though? It means that most of the time, putting a DK on a physical immune or magical immune enemy is going to gimp their damage somewhat - some specs worse than others! You may be better off leaving them on the boss and leaving your more 'pure'-type DPS to take care of the adds, in this case.
Common to all or multiple specs
- Pestilence: Non-damaging, but it is considered magical (and, fun fact, it can miss)
These are the spells you can look to see most DKs using in some capacity or another. All specs depend on Plague Strike and Icy Touch to at least apply the initial diseases; however, Icy Touch is considered magic, so magic-immune or frost-immune enemies can't be hit with it, thus preventing them from getting Frost Fever. Rune Strike is most commonly only seen being used by tanks or solo DKs, but it could be useful knowledge, so it's on the list. Necrosis and BCB can show up in a few different specs, so I included them here; they're passive, though.
- Sudden Doom (talent)
- Dancing Rune Weapon: it does the same damage as you do.
Blood is, in my opinion, the spec least likely to be bothered by a magic-immune enemy. Their damage will still be slightly gimped: Heart Strike will be doing less due to the lack of diseases - immunity to Icy Touch means no Frost Ever, after all - but at least Death Strike will be hitting at full power. Since the DK won't be hitting with Death Coils, anyone rocking the Glyph of Death Strike (which I believe is standard for blood spec these days) should be hitting for max damage with that strike most of the time. If you _have _to put a death knight on magic-immune mobs (say, due to a low number of raiders to choose from), I'd choose a blood-spec DK over the others.
Frost takes a pretty big hit if it runs up against a magic-immune enemy. No Icy Touch means no Icy Talons or Improved Icy Talons, a weaker Obliterate, and weaker Blood Strikes (because that attack really needed to be weaker...). No Frost damage at all means no Howling Blast and probably no Frost Strike. Don't put Frost death knights on magic-immune enemies.
Nature (yeah, you read that right)
- Summon Gargoyle (technically, the Gargoyle can melee, but usually when this happens it's a mistake - not something you want to happen)
Physical & Shadow
- Scourge Strike: This is an odd cat as of 3.3; Scourge Strike's initial damage is physical, but it follows immediately with shadow damage. It's more physical damage than shadow, though.
- Ebon Plague: Ebon Plague, since it doesn't do damage... I'm not sure. It's classified in the Shadow school, however, so it seems probable that it's Shadow. As it's a disease, though, and not magic, Plague Strike will probably apply it -- not that it'll do a lot of good for that magic boost.
Unholy is probably second-worst-off behind Frost. Scourge Strike will be operating at half-efficiency, the Gargoyle will be useless unless you can maneuver it close enough to melee (which it's really not that great at), and Unholy Blight depends on being able to hit with a Death Coil (which magic immunity guarantees won't happen). I'm still not too sure about Ebon Plague, to be honest, but in the end it wouldn't be too great even if it did get applied - it would only boost disease damage to a magic-immune enemy.
ik posted this below in the comments, and I think it pretty much sums up what I was trying to get at, but throws in some good advice as well.
When you say that Frost maybe takes the biggest hit from magic immune mobs, that might be true if you were using a normal rotation. But you won't.
The obliterates and blood strikes hit for 25% less for Frost.
Scourge Strikes will hit for 75% less, and that's without double dipping. Blood Strike hit for 37,5% less for Unholy
And that's really all the spells you use on the magic immune mobs.
Unholy death knights might even want to change to using obliterate on the mobs (as there's no diseases to remove), due to the massive damage reduction of Scourge Strike. But frost h
ave talents/glyph that increases Obliterates damage, which makes it hit a lot harder for them, and Frost use dual wield, achieving more auto attack damage. And as far of "not being able to get Icy Talons", targeting another mob, hitting Icy Touch from a distance every 20 seconds isn't that a big problem. And a windfury totem can replace it.
Tho ghouls help, but you don't need to hit the same target as them. I guess a /petattack targetX macro, would work wonders. But assigning an Unholy Death Knight to kill magic immune mobs, is like taking away half their damage and all the utility of an unholy dk.
As far as what the Unholy Death Knight can do. If you want to help killing the adds, get a blood dps off spec, or even blood tanking spec would be better. Or just tell the raid leader that you simply won't be on adds. And if he disagrees... well, then you can just equip Piccolo's flaming flute, you're not gonna be of much help anyways.