This is my apparel:

Robes : 25% Destruction + 25% Conjuration spell reduction cost

Ring: 25% Destruction + 25% Conjuration spell reduction cost

Also, I've got the perk for "Cast Adept spells for Half Magicka" perk in the destruction tree. But Ice Storm spell, which is Adept level, still costs me magicka and I'm out in about 9 dual casts with 600 magicka (nothing like the vids on youtube where it costs nothing to cast them).

I've used Grand Soul gems for enchanting my stuff. Is this the reason they don't work? I've also added/removed my apparel, but though the reduction shows up in 'active effects', it doesn't do anything.

Help, please?

EDIT: I've just been reading up, and sorry, I did not notice that you need to enchant 4 pieces of apparel with 25%. This works, true, but then the perks of cost reduction are completely pointless right? What is the reason for those perks, can someone please clarify?

3 Answers 3


I can't verify this b/c I am at work, but I was pretty sure those cost reductions were additive when they were from the same source and multiplicative when they come from different sources (ex. you add up the percentages from armor enchants, but you multiply for combining armor enchants with perks).

Again, I don't have access to the proper formula, but I thought it was something like

cost = (1-SUM_OF_ENCHANT_REDUCTION)*(1-SUM_OF_PERK_REDUCTION)*... for each type of casting cost reduction there could be.

So, if you had 50% from armor and 50% from perk, instead of 100%, you would have 75% reduced cost. You could test it by doing the same Magicka benchmark you just quoted without your armor on.

As an aside, check out the answer to this question for balancing your regen vs reduced cost vs. other stats. (not my answer, but I thought it was really useful)

One more note: the perk is particularly useful if you aren't trying to enchant your armor for free spells. That's especially important for a hybrid style character that uses some magic and some martial skills, or someone who wants to add resistance to their armor instead of cost reduction for some added durability vs. magic users.

  • Thank you for the answer. Only one thing now remains to be verified - if I can make 75% reduction via enchanting, and 50% via perk, will I achieve free? Because that would leave some empty enchantment slots.
    – Aditya M P
    Jan 6, 2012 at 16:45
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    (1-.75)*(1-.5) = .25*.5 = 0.125. No. The only way to get the cost down to 0 is to make 100% reduced cost enchantments. However, when your spells cost 12.5% of their base cost, you might achieve endless casting with high enough regen. Jan 6, 2012 at 17:03
  • SPOILER: I just defeated the world-eater with 100% Destruction and Conjuration cost reduction. Thank you for the help :)
    – Aditya M P
    Jan 6, 2012 at 19:45

You shouldn't get free spells from cast reduction cost. Free spell casts would come from a really high magicka regeneration, as well as a spell reduction cost.

If a spell normally cost 100 to cast, with your current equipment it should cost 3 magicka.

The point of the perks is if you don't have equipment which reduces spell casting costs. They are also "required" perks for other more useful perks if you do have the equipment.

Remember that the game allows "warriors" to also take perks in spell casting if needed.

  • Thank you for answering. Please read the edit I posted, can you also answer that one? thanks...
    – Aditya M P
    Jan 6, 2012 at 9:35

As you say, you need 4 items of -25% destruction. (There are other ways, I only have 3 items but that involves double enchanting).

Sorry to be the bearer of bad news, yes all those spell reduction perks were a waste... :(

The only time spell reduction perks are useful is when you don't have you -100% equipment on.

  • This is good to know, as I just started a new game and going for that. So the Perks are better invested into Enchanting and Smithing, correct? Jan 6, 2012 at 10:24
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    @SebastianP.R.Gingter What you put your perks in to is up to you. The beauty of the ES games is that there is no right way to play them. You can be an Unarmed Bad@ss if you want to (language may be NSFW), or take an arrow to the knee.
    – Xantec
    Jan 6, 2012 at 13:07
  • @SebastianP.R.Gingter Sure, you can play anyway you want. But, you'll use Smithing and Enchanting over 9000 times, so they should definitely be upgrade.
    – Coomie
    Jan 7, 2012 at 6:18

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