Ok, boys, I'm here to lay down the real shit on ED.
1) ED's "spell damage modifiers affect DoT" means exactly that - ALL OF THEM. From passives, from jewels, from gear, from support gems, increased or more - doesn't matter - THEY WORK.
2) That means all of these damage mods work on ED (and also on poison and decay that are inflicted by ED) - chaos dmg, generic dmg, dot, projectile dmg, spell dmg.
3) ED is a purely single-target skill. In order to make it have good aoe clear, contagion is used. Contagion is not a damage skill, even though it does some damage. The two most important things to scale with it are its aoe (so it could cause multi-screen cascading desctruction) and its duration (which should be no shorter than ED's duration). Adding cast speed is also nice.
4) That covers most of aoe clearing capabilities of an ED build. You cast contagion over a pack, you hit any affected mob with ED, it melts, then everything else in that pack melts, then everything else near that pack melts, and so on until ED's original duration timer runs out.
5) You want to have a good aoe clearing capabilites - you get 1 (one) duration cluster on the passive tree. It really helps.
6) Blue packs will take a bit longer to clear that way. Solution - abyssal cry. It scales really well with most of what you get for ED. Link it with inc aoe and void manipulation gems. If you can spare the 4th link (and you really should), add poison (unless you get that from consuming dark or cospri's). Optional fun: you can also link life leech gem to it, and it'd heal ya real good. Also, it's the one skill that would let you be amazing in party play.
7) In order to make ED have good single-target damage is to slap poison and/or decay on it. It makes the difference between ED being "meh" vs bosses to it being one of the best non-bugged boss-killers in the game (except vs two poison-immune bosses).
8) Poison is da best. Because it will inherit all the ED's damage mods, by double-dipping fuirously. Also benefits from that duration cluster that we must take for contagion. HUGE damage. And it stacks.
9) Get that poison via poison gem, cospri's will armour (if you are playing a non-CI/lowlife ED), or the consuming dark dagger. All three choices are good depending on your build variant.
10) Add decay (via essence of delirium craft) on top of that for another very strong non-transferable single-target melter, that also laughs at poison-immune enemies. You want both eventually, really.
11) The best 5-links for ED are: ED + controlled destruction + void manipulation + rapid decay + slower projectiles.
12) 6th link choices:
*poison - actually a 5th link instead of slower proj if you get your poison via gem. SP becomes the 6th link for this variant.
*empower - worse than the rest, but is the best if you're a rich bitch and have a +1 gems armour and a lvl4 empower. Otherwise don't bother, because it doesn't double-dip with poison/decay.
*pierce - if you want that pierce for some weird reason (you don't, and if you do, better use those shaper's boots instead, they're real good). Strictly inferior gem choice, but at least it double-dips.
>if you're into PVP, keep the LMP/GMP gem around, it'll make short work of any non-CI build if you can land a hit.
13) best weapon choices for ED:
*crafted essence of delirium dagger (sai base) with decay mod, with extra spell damage and/or dot (leo's mod) on it - sai for whirling blades and extra block, decay for superb single-target damage (also helps with aoe clears by killing the first mob much faster), extra damage mods are just gravy.
*the consuming dark dagger -"free" poison on hit and decent damage boost. Best complimented by another strong damage-booster in another hand. If you get your poison from elsewhere, pick other weapon.
*breath of the council scepter - good aoe boost, great skill duration boost, decent skill damage boost. All round a good choice. The only drawback - it's not a dagger (now whirlies for you). Solution - dual-wield with dagger, or use with shield for shield charge as movement skill.
*bino's kitchen knife dagger - only good for poison proliferation. Means you must have poison on ED, or this dagger is utter shit. Then again, it only really helps with aoe clear speed, and it's shit vs bosses. Once you can afford the decay mod dagger, bino's goes into the dumpster.
*a shield - if you must use one, pick the es base with a strong spell damage mod.
14) best flasks for ED:
*witchfire brew - extra double-dipping damage, extra damage aura-curse, and defensive boost as well.
*the dying sun (aka shaper flask) - extra projectiles for ED, extra aoe for ACry and contagion. Superb aoe clear speed flask, iuf you can afford it.
15) best ascendancies for ED:
*witch (occultist) - the only source of enemy chaos resistance reduction in the game. Must go CI with it, and make good use of its ES recharge mechanics. +1 curse ascendancy is a great bonus.
*shadow (trickster) - definitely weaker than occultist, but still half-decent. Haven't tried it.
That's all there is to ED. Nothing else to discuss here. This shit has been done by multiple people multiple times, these are the best practices. You want to try something else - don't run back crying that ED is shit. It's not ED, it's you.
...Oh, and then there's my iron will berserker variant, but it's a special advanced variation (still up there with the best of them), and I'm too lazy to discuss it here. If you're new to ED - stick to basic routines.
