The discussions tend to be around healers going OOM early in a heroic dungeon, so apparently you need 3 strong DPS (with the unspoken assumption of a zergish approach). While this is a perfectly acceptable approach, and may even be conventional wisdom, it is by no means necessary.
One in response to this comment : The only place I've heard people even consider taking more than 1 tank or healer to 5man dungeons is from gold making websites! The PUG and I collect tanks and healers; 70% of my regular players have a tank. I have been slightly short on healers, and very short on DPS.
Stupid (adj) : lacking ordinary quickness and keenness of mind; Those reading after the break may be mildly offended.
Most of us either being Wrath babies (or simply spent a long time in Wrath), ordinary heroics means the 15 minute zerg dungeon. Now we are in Cata, when we stand in the fire, we are stupid. When we don't interupt we are stupid. Treating mobs like an AOE tank and spank is stupid. Yes, this applies even when we don't know the fight yet. I am a firm believer that stupid can be cured, with training and experience. Conventional wisdom mitigates stupid by extra DPS (less time to be stupid), but extra healing (forgivness of stupid untill you go /oom), or mitigation (stupid doesn't hurt so much) also work. Conventional practice mitigates stupid by overgearing.
Back in Wrath, deaths were usually a one or two-shot event. Either you outgeared stupid (giving extra DPS, healing and mitigation), or stupid = dead.
In Cata, healers go OOM in dungeons when they heal stupid, or when they dispel stupid. OOM means dead. This is meant in the kindest possible way. Given the newness and difficulty of cata dungeons, there are a lot of opportunities for stupid.
In my failed Stonecore run last week, I took the second most amount of damage as healer. Stupid.
While healing Heroic Vortex Pinacle , I was called on to mass dispell the static cling every time, on widely seperated groups. I did this. I went OOM because it was stupid. Static cling is largely predictable, avoided by jumping. My DK tank doesn't get hit by it, because I spend the entire fight jumping (no stress easy mode). My healing priest got hit every static cling. Jumping during static cling immediately after chain lightning should be easy to remember, instead the group (including me but not the tank) were stupid. The run was successful - just. It could have been easy.
To explain why I don't need tank + heal + 3 Damage dealers in a heroic, I will start off with some approximations of an initially fail group scenario.
- No one dies significantly stupid, but players take damage from minor stupid.
- Tanks take 1/3 the damage of the fight, mitigage 1/2 of this, and provide healing equal to 1/4 a healer. (Note: on some fights my DK tank does more healing than the healer).
Scenario 1 : 1 tank, 1 heal, 3 DPS. Each DPS does the same amount of damage (7K each), and the tank does about 1/2 the total damage (say 4k), with the healer doing 0 damage, and has 50 seconds of mana (with 10 seconds of healing done by the tank). Total DPS is approximately 25K dps. Boss has 2M health, no self healing, no enrage timer. Fight lasts approximately 80 seconds, but healer oom at 60 seconds means wipe.
Scenario 2: 1 tank, 2 heal, 2 DPS. Total DPS is now 7 + 7 + 4 : 18 K Dps. Healers last 50 seconds each, meaning 110 seconds of healing. Fight now lasts 110 seconds, so healers are oom, but boss is defeated.
Scenario 3: 2 tank, 1 heal, 2 DPS. Total DPS is now 7+7+4+4 : 22K DPS. Tanks split boss damage. Healer now lasts 70 seconds due to extra mitigation, + 10 + 10 (from tanks), so 90 seconds of healing for a 90 second fight. Healers are again OOM, but boss is defeated.
The reason for 3 good DPS in a heroic is that completing the fight quickly allows less time for stupid. Unless you have an enrage timer, extra healing or mitigation in whatever form makes the fight easier. The cheapest mitigation is to learn not to be stupid.