Illusion just for invisibility: how much magic?

[Su8tle]

I'm intending just to use illusion for invisibility to complete my rouge build. How much magic will I need? I'll be going up the illusion tree till I get the expert at half price perk (illusion is only an expert spell yeah?) and up the other side till I get quiet casting. How much magic will I need? I'm at 150 now, and I only want the min I'll need to cast semi regularly.

 

[Dagmar]

334 is the base magicka cost. It reduces as your Illusion skill increases and costs 41% less when you have 100 Illusion skill. The skill modifier precedes the perk modifier so if you have 100 Illusion skill it gets reduced to 197.06 and then with the perk modifier it gets further reduced to 98.53 which the game will probably round up to 99.

Keep in mind that without the Quiet Casting perk, the spell is a bit loud and will alert enemies to your presence if you cast it within earshot. With a duration of 30 seconds you'll have to move to your goal relatively fast if you don't have the Quiet Casting perk.

Are you using Alchemy? You can make Invisibility potions that will last longer and wont create any noise (the last batch I made have a duration of over 100 seconds). Then there's always the the Shadowcloak of Nocturnal power.

 

[Su8tle]

So at 150 magic already, I could just stay with that and concentrate on stamina/health?

I am investing in alchemy. But due to a Rogue build and in the interests of an accurate roleplay build a Rogue should use Illusion magic. Plus it'd just be fun with illusion in one and and the blade of woe in the other. With 100 sneak and 100% muffle. What couldn't I sneak up on???

 

[Dagmar]

150 should be fine. If you're going to take the Quiet Casting perk you may as well get Pacifyto benefit from the Kindred Mage perk that you have to take along the way. As means of magical subterfuge it fits with the Rogue profile.

 

[Su8tle]

Thanks for the tip!

 

[ShenziSixaxis]

Just to add, another thing to look into would be a ring or other little item that adds magicka points or reduces the cost to cast certain spells (i.e. illusion).

 

[Su8tle]

I'll eventually be adding reduce illusion casting as one of two enchantments on my final helmet/cowl whatever it may be.

 

[Professor Skalvar]

If you wish to add more power to the duration of the Invisibility spell, Vampirism is the way to go. It makes all Illusion spells 25% stronger. Dual-casting it should make you stay invisible for a little over a minute.

 

[Dagmar]

If you wish to add more power to the duration of the Invisibility spell, Vampirism is the way to go. It makes all Illusion spells 25% stronger. Dual-casting it should make you stay invisible for a little over a minute.

Everything I've read on the subject indicates that neither dual casting nor the Champion of Night perk affects the duration of Illusion spells, only their strength, i.e. the level cap for creatures affected by Illusion spells.

 

[Drewski]

Maybe worth noting here, that dual casting invis makes it last for c. 72 seconds (with perk). This is quite useful at mid lvls, if you want to avoid whole sections of dungeons.

Also worthy of noting:- Once you have filled the sneak tree (actually just having high sneak will work), have muffled boots, x30 backstab modifier, and can turn invisible at will....well it's a build that becomes very quickly boring. My char with this build, went from lvl 30 odd to 40 odd, without a dagger ever leaving his right hand, and an invis spell leaving his left hand.

It became just too easy I'm afraid. Muffled boots, max sneak and invis all the time...well you're just undetectable, and if somehow a backstab fails (very, very rare), you just turn invis again and repeat.

Quiet casting perk is an absolute must though.

 

[Dagmar]

Maybe worth noting here, that dual casting invis makes it last for c. 72 seconds (with perk). This is quite useful at mid lvls, if you want to avoid whole sections of dungeons.

I just tested this on my mage and it's actually 66 seconds which makes sense given the multiplier for dual casting perks is 2.2. I also tested it for Alteration and Restoration spells that have durations and increases the duration for those by 2.2 as well (Conjuration was already known from the description of the perk and Destruction has no spells with a duration).

 

[Drewski]

I just tested this on my mage and it's actually 66 seconds which makes sense given the multiplier for dual casting perks is 2.2. I also tested it for Alteration and Restoration spells that have durations and increases the duration for those by 2.2 as well (Conjuration was already known from the description of the perk and Destruction has no spells with a duration).

You are of course right

I was adding the two spells durations together and then adding 20% ((30+30) +20%) which would give 72...and its actually just 30 +20% +30 =66

But I was doing it off the top off my head (without the game on), and I did say circa 72

 

[Black-Tongue]

Keep in mind that without the Quiet Casting perk, the spell is a bit loud and will alert enemies to your presence if you cast it within earshot. With a duration of 30 seconds you'll have to move to your goal relatively fast if you don't have the Quiet Casting perk.

Are you using Alchemy? You can make Invisibility potions that will last longer and wont create any noise (the last batch I made have a duration of over 100 seconds). Then there's always the the Shadowcloak of Nocturnal power.

Bingo. Personally I enjoy casting spells and not relying on materials, but in this case the potion soundly thrashes the spell.