0% magika cost using perks

[Nameless233]

If u have the perk that halfs the cost of magika of, let's say expert level destruction, and u also have the enchantment 50% less magika cost for destruction, does it become 0% magika cost for expert level destruction spells?

 

[psyk0]

I know it works for enchanted items, so that if you have four items that each provide 25% reduced magicka cost for a school, you'll have 100% reduced cost and therefore free casts.

However, I don't think it's the same with perks. According to the UESPWiki the formula for spell cost is as follows:

spell cost = base cost * skill multiplier * perk multiplier * equipment multiplier * dual cast multiplier
skill multiplier = 1 - (skill/400)0.65

Let's assume a spell's base cost is 20 mana, you have 100 skill, and you've got 50% reduction from the perk and 50% reduction from equipment. Let's also assume you're single-casting it.

20 * 0.65 * 0.5 * 0.5 = 3.25

So the cost is reduced to almost nothing but it's still not free; this is because the reduction from perks and the reduction from equipment are calculated multiplicatively, not additively.

If you've got 100% reduction from equipment, the equipment multiplier becomes 0 - therefore regardless of any other factors, ultimately you're multiplying by 0 - therefore the cost is 0.

 

[Dagmar]

Let's assume a spell's base cost is 20 mana, you have 100 skill, and you've got 50% reduction from the perk and 50% reduction from equipment. Let's also assume you're single-casting it.

20 * 0.65 * 0.5 * 0.5 = 3.25

The skill multiplier at 100 skill is 0.6 not 0.65.

 

[Nameless233]

Ya I don't really like have 0 magika cost, makes it way too easy for me especially if it's for destruction, anyway hanks for ur help

 

[psyk0]

The skill multiplier at 100 skill is 0.6 not 0.65.

Ah, you may be right - I'm only taking my numbers from a wiki. Apologies.