I have shocking information! Is everyone sitting down? Not everyone in Outland five-man pugs seems to grasp the benefits of dropping mobs in a specific order. I present exhibits A and B.
A) I was leading a pug through Blood Furnace the other day. We got to the the trash pulls which include the Hellfire Imps. I marked the kill order, starting with the imp, and in we went. After the pull someone asked why we started with the Imp. It’s just a wee little Imp, after all! I tried to explain that it does a lot of spell damage, unmitigated by armor, and is relatively weak so we can kill it fast. I don’t remember their specific response but it was clear at the time that they had no idea what I was talking about. I smiled and nodded. To their credit, they may not have understood the reasoning behind the kill order but they were dutifully attacking the mobs in marked order. On we went.
B) Fast forward a few more pugs. BF again, this time being lead by someone in plate claiming to be a tank. I don’t remember where exactly, but one of the pulls had a few melee mobs in it. The tank’s cunning plan was to have each of us take on one of the mobs by ourselves. I made some crack about there being better ways to maximize incoming damage but I’m not sure they got it.
Self, I thought, some training is clearly in order. Wouldn’t it be nice if I had a post that I could point people at in the future when they ask about this stuff? Here goes.
Why do we focus fire and drop a mob at a time? We do it to minimize the amount of damage that a group of mobs have the chance to do. And why do we do that? So that our healers spend less mana healing. And why do we do that? So that we spend less time waiting for them to drink after they’ve run out of mana after a few pulls.
Why do we focus fire in a kill order? To go faster.
Let’s say we have three group members — A, B, and C — and three mobs — X, Y, and Z.
Each of our group members does 1 damage per second. Each of the mobs each has 3 health and also does 1 dps.
What happens if each of the group members attacks their own mob? That is, A attacks X, B attacks Y, and C attacks Z? They’ll each take 3 seconds to drop their mob. Each of their mobs will be alive for 3 seconds. The group takes 3 + 3 + 3 = 9 damage. The healer has to heal 9 damage.
What happens if all the group members attack each mob in turn? That is, A, B, and C all attack X. Once it drops they move on Y and then on to Z. Each mob will be alive for the number of seconds which corresponds to its position in the kill order. X is alive for 1 second, Y for 2, and Z for 3. The party takes 1 + 2 + 3 = 6 damage.
By focusing fire the group takes 6 damage instead of 9. The healer has to spend 33% less mana.
33%.
I like to think of focusing fire as a cheap and very powerful healing buff.
This simple model assumes that all the mobs do the same amount of damage and have the same amount of health which is not the common case. The Imp from the opening example does more dps than the other mobs in the pack and has less health. The amount of damage avoided by killing it first is more dramatic than in our trivial example.
It’s kind of interesting to notice that the fundamental design decision at work here is that, in general, mobs do the same amount of damage no matter how much health they have. They’re either doing full damage or they’re dead. One could imagine tactics changing quite a bit if mobs did less damage as they took damage themselves.
That’s my take on all this, anyway.
Now we’re all either proud of our habits of focusing fire or are excited to run out and give it a try, confident that our healers will give us big hugs, right? Right.