Often, while leading or planning raids, I have to experiment with new ideas, and utilize game mechanics in an interesting (if non exploitive) way. It often surprises me when I say to do things a certain way, so many players aren't aware how the fundamental mechanics behind some of the plans I try to implement work. Specifically, there's a few areas that are poorly understood, but can make the difference between a successful raid and an outright failure, and I see even extremely experienced players make the same mistakes.
1. Proc versus cast from mobs.
This is probably the single most confused thing I see from players that start raiding new with me, and I even see very old raiders sometimes not make the distinction. It's an important one, at least from a raid leader's point of view though.
A cast from a mob is differentiated from a process most simply by the mob always giving a cast message for it. So and so casts a spell is required for any cast, and absent from any actual proc. That's a good way to distinguish them, but what are the differences that actually matter? Well, first off, a cast is restricted by recast recycle from a mob. Let's take for example Trakanon's ae, Poison Breath. It has a recast of 35 seconds, 0 cast time, 0 mana cost, and it's flagged interruptable. What happens is every 35 seconds as the spell refreshes, Traknon's AI will check. If he's not busy doing something else, he'll cast it (0 sec cast, so it goes off pretty much instanteously from his cast). Him being oom doesn't matter, because it has no mana cost. It's possible he could cast a little slower than 35 seconds, since he might be in the middle of casting some other spell, or the AI could be otherwise 'busy'. So you sometimes see a few second delay after what the recast of a spell would be. Also worth noting is his cast is marked interruptable. The chance of interrupting a 0 cast time spell is immeasureably low, because only stuns and melee during the exact same timestamp of the cast is checked, a fraction of a second. However, a lucky air pet cast stun sometimes will do it, and if you are fighting 0 second cast spells that are for some reason marked interruptable (a lot of older content is, while newer is not), you might find it to your benefit to use as many air pets as possible.
Now, a process checks on every swing of the mob for a chance to fire, like a player would. Recast time for spells on a process don't do anything, there's no check against them. Now, one important thing to note is even spells that are naturally AE's aren't necessarily an AE when put as a process on a mob. They can either be marked as single or marked as AE, and AE processes are (thankfully) VERY rare. There's only about a half dozen mobs in the game that have true AE processes, and generally a lot before were bugs. There's a good reason for that. Today's raid mobs generally attack several times a second, usually with delays around 4. This means often they could swing 12-13 times in a single second (counting kick/bash), or around a hundred times in the space of a CH. Now, if every chance of a swing can yield a 3k point AE, you are looking at tens of thousands of AE damage in the space of most heals. Very, very few mobs have AE damage processes.
But single player targetted processes are pretty common. Take Deadly Lifetap, from many mobs from Venril Sathir up to nameds in City of Decay. An excruciatingly popular proc as many raid leaders will become well aware. Often, you'll find with procs like this 1500 point lifetap proc that the taps are more dangerous than the actuall melee of the mob. A few important notes- there's 2 types of procs from a mob. Ones targetted on a single -player- need to actually do damage to fire. The explaination for this is actually kind of a roleplaying reason- the original dev team didn't want snakes in east commons or rabid animals procing rabies or poison on people that actually didn't get hit. So unlike players, runes, misses, and dodge/parry/blocks all prevent (most) of them. For example, originally on venril sathir when most warriors had all of 4k or so buffed and a couple procs back to back would flatline them, it was pretty popular for us just to send in someone using riposte disc instead of defensive. But you should note not all procs that fire in melee have to be targetted on a player. Procs targetting self -never- have a check for damage on the target in melee. A painful example of this is the Divine Aura procing hammer wielded by that mob in Grieg. No, he doesn't need a successful hit to proc DA on himself... again and again.
Lastly, yes, mob procs can fire from ripostes. On an npc that procs for 3k, it's a very, very bad idea to have all melee fighting from the front.
2. Mob AI, aggro logic.
There's so, so, so much confusion over mob aggro AI, and it's pretty annoying for a raid leader to sort it out.
Probably the most annoying myth is the belief all mobs aggro in the same way. This is pretty easily demonstrably false. What most players don't realize is very frequently raid mobs use almost as many aggro difference as an orc, a puma, and a skeleton use in east commonlands.
The puma hits sitters. The skeleton trains off and hits anyone. The orc doesn't care. So what does this have to do with raid mobs?
Most importantly, you can split mobs by knowing which aggro they have. For example, in one of the LDoN time level raids, there's the Rujarkian Experiments. Some nameds are behind some small rooms with about 40 or so guards, and presumably you are supposed to clear them out. A conventional split would be agonizing for the sheer amount of mobs involved and bad space to work with. But I noticed the guards had very poor awareness aggro versus their initial assist aggro. So I divine aura'd myself, ran through, aggro'd 40+ some mobs in a huge train, trained the name about 200 range from the range with all the mobs beating on me, an enchanter tashing the named (which peels off and goes running at the raid), then I move all 40+ trash mobs away and die. They reset, they don't aggro the raid. It surprised me that most of the players I played with were confused by why it worked, and I think it does merit an explaination.
Mobs carry a few different aggro settings on them. Firstly, mobs behave differently based on proximity. For example, the skeleton in east commons (or a raid mob with nearly identical AI, the Avatar of War). He constantly checks for the closest target and attacks, granting a massive hate modifier to anyone that stood underneath him. Now the -level- of this modifier is important. For example, AoW pretty much just hits whoever is meleeing him that's the closest, unless there's a huge gap in aggro. It follows that by degrees- for example, there's some dragon sized models where at 150 range you will more or less never get aggro unless all melee underneath it are dead. However, if say a cleric walks up underneath it, the dragon will immediately spin and one-round them, since they've dramatically increased their effective aggro by moving into range, pushing them above the tank on it. Positioning then, based on mob aggro, can be vital.
Next, how aware of 'assists' they are is also based on how proximity aggro they are. For example, giants in Kael Drakkel. Generally speaking, they don't recognize indirect aggro at a distance. A cleric buffing or healing a tank after he had time to build up aggro often won't be added to the aggro list whatsoever because it's such a low aggro check it just isn't added to the hatelist. It's so pronounced among some very proximity aggro mobs that healers and buffers will need to cast some offensive effect in order to guarantee they get faction hits, and friendly-faction type healers could easily exploit it, provided they are never hit. More importantly, staying at a range kept them from ever possibly getting aggro and dying, and you can frequently split proximity mobs because their 'assist' is so much lower than their initial aggro on someone they just don't add a person to the hatelist if you attack a second mob while they are aggro. On the flip side, there are some 'bouncey' mobs that really don't care much about proximity, and will fly off someone very easily based on aggro at a distance, or train towards someone that attacks a same faction mob while they are already aggro on someone. Usually one or two checks of mob AI will let you know if something is possible.
3. Dispel logic.
So, so many people don't understand how dispels work. Practically every thread you see on them complain about dispels being at 'random', which they are one of the most consistent, easily predictable mechanics around.
It's important to understand that buffs and debuffs are tracked by the level of the caster, and dispels go by their level plus a dispel factor (often listed in a spell, like Cancel magic being dispel (1) versus recant being dispel (9)).
Dispels work like this: Dispel strength added to level of the caster of dispel hits the target. It checks the top buff/debuff slot on the player, and the level of the debuff/buff (so a debuff by a level 80 dragon is not the same as a buff by a level 65 cleric). Makes a random roll, and if the dispel fails to beat the buff/debuff's strength, then it checks the next buff/debuff down from top. It keeps checking until a dispel succeeds, or it fails -all- of them. Very important, a multislot dispel only checks against the top buff multiple times if it runs out of other buffs to check, otherwise it continues down from last dispel.
So in practice, here's what happens: 2 players decide they want to have a level 70 mana drain debuff cured off them, and they are going to get hit by recant. Both clear their top buff slot, but player A clicks off all buffs, while player B just clicks off top one, and has 10 other buffs below it.
Recant fires at player A: First dispel check fails, second dispel check fails, third succeeds, fourth does nothing. His mana drain is dispelled. Recant fires at player B: First dispel check fails so it checks buff slot 2 and dispels that, second dispel check goes down a buff and checks buff slot 3 and dispels it, third dispel checks buff slot 4 and dispels it, forth dispel checks buff slot 5 and fails, then dispels buff slot 6. This is especially important with the short buff box for bard songs, since the choruses will absorb dispel attempts.
That's all I really have this second, feel free to add in criticisms and comments on things I overlooked or got horribly, horribly wrong.:)
Cal