To find out the truth, I bought a two-handed weapon with 0.9 attack speed and a one-handed weapon with 1.6, both with the same rated damage per second. I then tested every spell on the zombies at the start of Act 1 in hell mode dozens of times and checked the damage difference, finally adding attack speed rings and amulets and re-testing both weapons. For almost every spell, the one-handed setup dealt lower damage but hit more frequently, averaging to the same damage per second. But the story was a little different for Hydra, Blizzard, and channeled spells.
In this guide, I put five popular Diablo III Wizard myths to the test and discover the inner workings of Energy Armour, Hydra, Blizzard, Critical Mass, and other abilities.
the damage of each bolt is normalised based on your attack speed at the time of casting. In my tests, I found that the damage dealt by each hit and the total damage dealt over the lifetime of the hydra were the same with both the one-handed and two-handed weapons. Increasing attack speed further with rings and amulets similarly increased the damage of the Hydra bolts. Interestingly, Hydra also ignores the damage range of your weapon, so a dagger with a huge damage variance will deal consistently average hydra hits.
Channeled spells like Ray of Frost and Disintegrate are also boosted by attack speed. The damage numbers from the spell's hits pop up at only 0.5 second intervals, but the actual tick rate is faster, and the UI just reports the accumulated total every 0.5 seconds. Blizzard's damage over time effect is based on your weapon damage just like most other spells, and increased attack speed lets you cast it faster. However, the damage from multiple Blizzards in the same area doesn't stack. This may be a bug, but for now, Blizzard is the only Wizard spell that does not have its damage per second increased by attack speed.
every spell has its own coefficient that determines the percentage of life-on-hit gained per target struck, and spells that can hit multiple targets tend to have lower coefficients. Magic Missile will heal for 100% of your life-on-hit, but Blizzard will return only 2% for each target hit, and Hydra won't heal you at all. This has led people to use popular kiting builds to assume life-on-hit doesn't work properly with spells even though all other spells have much higher coefficients.
This seems to be Blizzard's way of balancing spells that are likely to hit multiple targets, and it goes way beyond just life-on-hit. Arcane power on crit returns are multiplied by the spell coefficient, and Magic Weapon: Venom uses it as its chance to proc. Testing indicates it's also used for Arcane Dynamo, Paralysis, Critical Mass, and everything else that has a chance to proc. A list of spell coefficients is available on the US forum, but you can test it yourself by getting some life-on-hit gear and killing zombies in Act 1 normal to see how much healing is returned for each spell.
increase your damage per arcane power as you'll be casting fewer spells to deal the same damage. As a result, you're less likely to run out of arcane power.
Two-handed weapons are popular with kiting builds that use blizzard and hydra to keep mobs at arm's length and stop periodically to fire back arcane orbs, but there is an alternative. Wands, source offhands and helms can all have a stat that grants up to 10 arcane power on crit at level 60. If you have a high enough critical hit chance and use area-effect spells with high spell coefficients, you can actually regenerate 100% of the arcane power cost of spells. This works particularly well with Arcane Orb: Tap The Source and Meteor: Star Pact, and some builds use signature spells to regenerate arcane power.
certain attacks ignore force armour entirely. All of these turned out to be wrong.
Hits for between 0% and 35% of your maximum life are dealt as normal, and hits between 35% and 135% of your maximum life are reduced to 35% as before the nerf. Any time you're hit for over 135% of your maximum life, 100% of that will be absorbed and you'll take the rest as damage. This means a hit for 136% would deal 36%, a hit for 199% would deal 99% of your HP in damage, and a hit for 200% would be instantly fatal. If you're being one-shot through Energy Armour: Force, the solution is to get more vitality.
In my testing, I confirmed a few other things that have been floating about on the Wizard forum. The percentage damage bonuses from Familiar: Sparkflint, Magic Weapon, Conflagration and Cold Blooded are added together into one percentage damage bonus, yielding slightly smaller results than if they were multiplied together. Sparkflint bolts proc Conflagration, and as Spectral Blade deals any elemental damage on your weapon, it can also proc Conflagration, Temporal Flux or Paralysis depending on damage type. You may also have noticed that Magic Weapon is providing a much bigger damage bonus than it should be, but I found that this is just a UI bug and doesn't affect your actual damage.