Why stackable magic spells are hardly used in battle despite being the most powerful kind?

Question

A certain magic spell can cast its effect over an area, which is often known as area of effect spell. One such notable spell is chill spell, which slows target metabolism and movement. However, as chilling as its name suggest, 2 chill spells from different users don't necessarily increase the potency; therefore, it is not a stackable spell!

The blizzard is also an area of effect spell; however, it can quickly buries people or objects in a thick piles of snow and ice as more similar spells are casted on top of one another or in another words they stacks up.

Since both spells require the same amount of concentration and talent, I wonder why blizzards are not as popular as chill spells since they share the same preparation time and energy consumption?

Some examples such as instant heal magic vs stackable health regen and heat wave spell vs stackable floor is lava magic.

Answer 1

Because it's a waste of resources. Any supply is always limited, and you want to use them wisely. Using two spells on the same area means that you are left with another area totally unspelled and uncovered. It's the usual story of the blanket too short: if you pull it above your head it exposes your feet, and if you cover your feet it leaves your head outside.

If you are covering an area with ice, chilling the humans in that area seems like a waste. On the other hand, if you are just chilling the humans maybe it's because you want the area free from ice for yourself to quickly occupy it, so again blizzarding it seems like a poor choice.

Answer 2

It's all about duration:

If I'm following the trends here, your stackable spells are almost all duration spells. Snow accumulates over time, while chill is instant. Regeneration happens over time, while healing is instant.

Battlefields are dynamic environments. If you drop a snow spell, your opponents can adapt to the change in the environment. They can move around the snow, or over the snow, or push a path through the snow. The weak flunkies might even throw snowballs at you fire elemental and damage it. The snow requires multiple applications and is time consuming. The snow could become as much a burden for the caster as for the enemy, as the battle shifts and the enemy shelters behind the impassible (?) wall of snow you've created.

Now compare that to a fireball or it's equivalent. Sure, lava might damage MORE than a fireball, but a fireball happens NOW, there's no adaptation, and your enemy is unlikely to turn the fireball against you. I drove a DM nuts once by pointing out that my enemies firestorm was incinerating the structural components that held up the roof over the enemy mage's head. As the building collapsed on him, our last remaining player ducked out of the firestorm and collapsing building with one hit point.

The same applies to healing. A regen spell might heal MORE in total, but my warrior is in melee NOW. 10 hit point in the hand is worth 20 in the bush.

So the logic of you stacking spells is all about how the NOW is critical in a fight. Adapt or die, and don't give your enemy the chance to adapt.

Answer 3

You are asking for drawbacks, so I'll give you some:

1: Easy to dispel. Imagine if another mage could dispel a Chill or Blizzard spell. The dispel magic used against Blizzards works regardless of the size of the stack. This means that you need to time a lot of mages to cast your Blizzard at the right time to get the most out of it before it gets dispelled. Otherwise, you waste X mages while your opponent needs just the one.

2: increasing unpredictability in its size. If you stack, the area size doesn't stay the same. Casting repeatedly will cause the size to increase, but with each stacked casting, it becomes harder to control how it grows. You don't want a mass of blizzard clouds to suddenly break off and bury your mages.

3: hard to get rid off. It's rather annoying if you destroy an army or village, and then can't use that area until everything has finally melted. Not to mention that the melting of the snow could deal tremendous damage to the terrain through erosion. You came there to conquer, not to destroy everything you were trying to capture.

4: can backfire. You might designate the initial spot for the spell, but imagine if an enemy mage might be able to find the center of the spell and then move it? They might move it over your troops or mages and bury them instead. It doesn't have to be easy to do this, but a high enough risk that you don't want to do it. There are other options, of course; the point is that if mages can move the area that the blizzard happens in to be either harmless or harm your own troops, you might consider casting the chill spell instead to cover more area and make it harder to nullify.

5: empathy spell. Some kind of spell like mirror magic is available, if you accidentally hit it, you could bury yourself in your own blizzard.

6: the harm can be minimized. Imagine if the opposing mage can cast a spell to constrict the area of the blizzard. Instead of showering 1 large area with snow and burying a small army you are suddenly snowing down on 1 square meter. Not worth much of the effort, so instead you cast Chill once and cast a new one should it be nullified.

7: specifics. For example the instant heal versus the area heal. The instant heal can be specified to only heal those you consider an ally (or who consider you an ally), the area heal is indiscriminate and cannot be told who to heal or not. (I forgot you mentioned other spells than Blizzard and chill)

8: can be reversed. Imagine if a spell can reverse the effects, so instead of stacking a heal over time it suddenly starts tearing people apart. Or the Blizzard becomes a blazing hot day melting the snow that came before. It might not necessarily be bad as it adds to your tactical repertoire, but it also adds a huge risk when deploying stacked spells.

Answer 4

Precision.

Do you carpet bomb or nuke an area just because you can? No. You need a really good reason to do so.

And do you carpet bomb or nuke an area more than once just because they stack? Again, no. There is such a thing as collateral damage.

Answer 5

Friendly Fire

Typically, nonstackable spells have friendly fire turned off. When you cast Chill on an area, you can make it affect your enemies and not your allies. Likewise, you can use Heal on your allies but not your enemies.

Typically, stackable spells have friendly fire turned on. That means the Blizzard or Regeneration affects everyone in the area, friend and foe alike. This is enough reason for the spells to be less popular.

Answer 6

Here are some possible drawbacks which you might choose to use for balance:

Cost: You've said "all costs being equal", but this is a classic - a higher-level spell slot, perhaps.

Time: There's a tendency for area-of-effect (AoE) magic to be constant for anyone in the area, rather than instant upon touching the area. So a "zone of healing" works over time to heal your wounds, but can work on multiple allies at once. Or on enemies, if they capture the area.

Strength/Size/Duration: You can change it for different spells. In general, if A does everything B does and more, B will never be used where A is equally available.

Fixed effect/Status effect: If "Chill" in your example sets the temperature of everything in the area to 36° (1° below blood-temp), then it will substantially affect anyone there. If you set it to that temperature again, then ... no extra effect. The same would apply to a "Stasis" spell. Once it's applied, you can go on to less subtle "2d4 Cold Damage" spells.

Attention: Suppose the party has one healer who knows "Zone of Healing", but has to concentrate on it for as long as it will last. This might be stacked in theory, but if you only have one caster for it, you can't stack it in practice.

Crossing the streams: Another area-effect on the same area at the same time may injure the second caster unless the first one prepared for it. You can restrict this to only affect copies of the same spell, or only some spells. Or you could have your healer cast "Zone of Healing" on the foe's ground immediately, and let the opposing caster stun themselves or worse.

Lockdown: Non-stackable spells be nonstackable because they double as an anti-magic spell. This is good for locking down areas against opposing casters, at the cost of hindering your own mages. Helpful if you're up against an order of weedy mages but are working with big-club warriors.

Stickiness: Sometimes, you want to affect an area. Melt the ground, say. But sometimes, you want to affect the people in the area now, even if they move around later. Stackable spells tend to affect the area directly and those in it indirectly.

There are other methods you could use, but it's hard to say without more information about your world and style of magic. How common are casters? Can you cast the spell and move on to more magic before it expires? Are they fighting armies here or individuals? Are your spells very limited, or can you cast all day and into the night?

Answer 7

Diminishing returns

If you're looking for a reason why stacking sucks, you just have to add some realism to it.

Very powerful magic spells on their own may be very powerful indeed, and they may stack to be more powerful. Of course, there's the question of overdoing it, like dropping two bombs on a target, where the first one destroys, and the second makes the crater slightly deeper.

But really, if you're lucky, stacking a spell $n$ times means you'll have a spell that's $n$ times more powerful. In practice however, stacking is likely to lead to very diminishing returns. The first spell gives $100\%$ output. The first stack may give $+80\%$. The second stack $+60\%$. And so on. Meanwhile, you could use those wizards to each cast a different, non-stackable spell at $100\%$ output. So it's a better use of your wizards to not stack if there's even the slightest loss in stacking, and realistically there should be.

And there's so much better you can do with magic than linear escalation

If you're looking for a reason to discourage stacking, this is where my gamer brain has one word for you: combo.

Even assuming a perfectly linear magic, you get double the spell for double the output. A better use of magic would be to find the way different spells or magics interact with each other, and find which can create exponentially more powerful new spells or magics.

Why content yourself with doubling your damage output if cleverly using two smaller spells leads to absurdly more powerful effects. Cold plus cold is still cold. Cold plus blunt force may just shatter your enemy to pieces. Heat and cold may trigger massive explosions. When dealing with magic, mixing it up can lead to a whole lot of fun.

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In simpler terms, if you put a fire on top on another fire, it doesn't make a fire that's two times hotter. But if you set someone on fire and then beat them with a stick, now that's dramatically increasing your damage output.

Answer 8

If you read answers carefully you will notice that most of them boil down to tactic vs strategy. Non-stackable spells are tactical and stackable spells are strategic. The latter is much harder to use as strategy requires planning and a good grasp of the bigger picture.

While 'mana' and cast-time requirements can be the same for both types of spells, stackable spells put higher demands on mages in terms of timing, positioning, and execution. The floor is lava is a much more damaging spell if you are dealing with melee enemies who are trying to get to you, but it is only so-so if those enemies are already in melee range. The same goes for health regen: It is a superior healing spell when used appropriately (stack a couple at the beginning of an engagement), but it is rather mediocre when your tank is bleeding and the boss hits really hard.

Most people are so-so when it comes to strategic thinking. It is also easy to get overwhelmed in a heat of battle. Therefore, tactical spells that produce immediate results are preferred. Only those who can stay calm and focused, know their enemies, and can analyse the battle in real time are capable of using strategic spells.