Are the Master destruction spells useful?

I was wondering if the Master destruction spells are useful or just to show them off? I'm asking because it takes ages to cast and you can't hold them neither precisely point (Lighting Storm)...

Have you ever used them with a purpose?

I used them for the lols during fort attacks in the Stormcloak/Imperial war quests, since there are a lot of targets around you. You can also sneak up to groups of enemies while stealthy/Invisible and let off one of them to start the fight.

Other than that, I didn't use them much, for the reasons you mentioned. Of all the perks they put in the game, I don't know why there isn't a perk to make winding up Master spells faster. You're really vulnerable while preparing and holding them, since you can't move.

They are useful in two cases:

• You want to maximize Area Of Effect damage/effect. Extremely useful for clearing a room full of Draugr or other high quantity low level situation. Blizzard and Lightning Storm are useful to get their effects onto a group of baddies.
• You want to maximize Damage Per Second. Incinerate is surely better DPS in a 1-1 situation, Fire Storm is certainly better in a 10-1. At some point there is a line (which can be calculated with the casting/delay times) where the master spells become better DPS.

Like yx mentions, Fire Storm costs 0 magicka if you've made 2000 'iron daggers of elite banishment' (100 enchanting). And its fun as hell to cast and watch everything burn.

From a purely mathematical/mage perspective:

The higher the spell the less efficient. See below:

Firebolt - 41 Magika - 25 damage - 1.64 Magika/damage ratio

Fireball - 86 Magika - 40 damage - 2.15

Incinerate - 171 Magika - 60 damage - 2.85

Fire Storm - 1426 Magika - 100 damage - 14.26

1426 Magika used to do 100 damage with Fire Storm.

164 Magika used to do 100 damage with Firebolt.

It seems that the most useful spells are Novice level. Of course, with certain perks and armor this can be changed.

Personal note: Using Impact perk I can effectively infinitely immobilise 2 enemies with Firebolts and sure they don't do damage as quickly, but eventually I can wear them done to death. But shooting a Fire Storm I have to run away to recharge my mana (for 20 minutes).

Master spells HAVE to be cast dual hand, but do not seem to benefit from dual cast bonus. DPS of those spells is just poor. I'm pretty sure I'd get more DPS spamming dual cast Fireballs than through Firestorm and it's a LOT safer, it staggers them through impact and is ranged. There's also the issue that trying to hit 10 targets with a single Firestorm will never happen on it's own because you'll get interrupted before you can pull it of.

For sure I get better DPS spamming dualcast Thunderbolt (expert lightning spell) than the Master Lightning Storm as I could test against an Ancient Dragon.

Cast time wrecks the usability of those point blank master spells. Unless you got the Invisibility spell to back them up, I've practically never managed to charge up Firestorm in melee range because most attacks on you would interrupt it. I've given up using Lightning Storm against all far away humanoid opponents either because they'd just pull a bow and hit me every 3s with it which cuts a cast that lasts 5s ... It works great to kill Dragons in flight though because of it's LONG range and pinpoint accuracy.

Soo, I'd say about those spells : - Lightning Storm is used to snipe dragons in flight but only if you can maintain it running for the full kill - Firestorm is rather weak and hard to place because of interrupts, try to combo it with Invisibility - Blizzard, well I don't like cold spells because it feels like half the fights I do are ancient tombs filled with Draugr or Dwemmer ruins filled with constructs. Also, it kills my companion.

Lightning storm in particular kills dragons pretty quickly. And fire storm is useful if you begin to be surrounded. You could also use blizzard.