Does the effect of Fireball negate the spikes of Spike Growth?

Question

Would the "explosion of flame" from a Fireball destroy the Spike Growth?

In a session a ranger cast Spike Growth. A few rounds later a wizard flew up 60ft and cast Fireball into the center of the Spike Growth.

What, if any, effect would the Fireball have on Spike Growth?

Spike Growth is fairly vague in its detail of the "growth". The sentence "is camouflaged to look natural" seems to imply that the growth takes on the material of the ground, but does it take on the properties as well? Does it depend on the ground coverage of the "point within range" (e.g. brick road vs forest floor)?

Answer 1

Fireball spell has no effect on Spike Growth.

The text of Fireball says:

It ignites flammable objects in the area that aren't being worn or carried.

However, the text of Spike Growth does not specify that the spikes and thorns created by the spell are burnt, damaged or if the suffer from any condition given by fire, independently on the ground from which they sprout from.

A similar case consists in the Insect Plague spell: a fireball exploding in the middle of the area of effect does not kill any of the bugs (see Are the insects from the Insect Plague spell affected by other damaging spells?).

As a counterexample, have a look at the Web spell:

The webs are flammable. Any 5-foot cube of webs exposed to fire burns away in 1 round, dealing 2d4 fire damage to any creature that starts its turn in the fire.

How can you negate the effects of Spike Growth?

Recall that the spell has a duration of 10 minutes and must be maintained via concentration.

There are several ways to try to negate the effects of Spike Growth. The following list is not exhaustive:

• Using Dispel Magic.
• Damage the caster to force them in making a Concentration saving throw.
• Inflicting to the caster the incapacitated condition (for example, via Sleep or Hold Person spells).
• Kill the caster.
• Fly over the area of effect (this negates the effects only for the character flying, not for everyone).
• Cast an Antimagic Field: in this way the caster of Antimagic Field can safely walk in the area of effect, and works for them and for everyone within 10 ft of them.
• Use a sledgehammer to crack a nut: use Wish (just for sake of completeness)

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The description of each spell usually specifies what kind of interaction its effect has with other spells, if any. Of course, a DM could adopt particular and reasonable ruling: for example, a Fireball cast on the surface of a lake could produce vapor.

For the interaction between Fireball and Spike Growth, one may take inspiration from Neil Slater's comment to this answer:

A more reasonable interpretation of RAW (than taking damage from nothing) may be that whilst the spell is active dead bugs are replenished by the same magic that generated them in the first place. The spell is active and has a duration after all.

Hence, the spike and thorns are burnt by the fireball, but they are immediately replaced by new ones, created by the magic fueling the spell.

Answer 2

No, it does not negate the effect

Spike Growth is a concentration spell that says:

The ground in a 20-foot radius centered on a point within range twists and sprouts hard spikes and thorns.

Even if the fireball were to burn the spikes and thorns, the ground would just continue sprouting them as long as you concentrate, and fireball has a duration of only an instant, so any spikes destroyed would be instantly replaced. Therefore, does not matter at all if fireball can set the spikes on fire or not.

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P.S. I think it is not 100% clear-cut if fireball can ignite the spikes or not, but it is unlikely. Fireball can set flammable (as in: easily ignited) objects on fire. If a spell created a flammable object, then fireball could set it on fire, even if the spell did not explicitly say so. For example, if you used creation to create a sheet of paper, fireball could ignite it.

• Here however is not conclusive if the spikes are objects at all or merely a magical effect. I think even if you consider them not an effect, it is a matter of adjudication if plants would count at objects.
• Second, even if you consider them objects, it is doubtful if they are flammable -- the spell does not state they are, and most plants are not that easy to set on fire.

So for a DM to rule the spell creates flammable objects, while not impossible, would be somewhat of a stretch. As discussed above, it also does not matter.

Answer 3

Up to the DM.

There are no specific rules interactions that would cause spike growth to be affected by fireball. However, this comes under 'and the DM narrates the results'. Whenever there is something logical, cinematic, or exciting, the DM can and usually should include it in the narration. The field of brambles catching on fire would be a cinematic and interesting interaction of the two spells - whether this means the spike growth is gone, or now adds Fire damage when someone moves through it, is up to the DM. Perhaps both - after a certain amount of time the spikes will be burnt through, but until they do the heat and choking smoke will make them that much more deadly to move through.

I will reiterate - this is the intended gameplay of D&D 5e, as spelled out in the rules, and while there is much advice that the DM should never narrate results other than those explicitly described in the entries for spells, monsters and etc, I have personally seen that attitude destroy far more games than the opposite one.

Answer 4

I always like to think that if the books don't say how it works, then the dm decides. In this case the book does not say that if the spikes are effected. I would say do whatever makes the players happier. You want them to stay engaged after all. I had this very thing happen when I was DM for my students (I use dnd in a creative writing class). I declared the spikes catch on fire and the area will do 1d6 fire damage at the beginning of a creatures turn if they start in the circle or they enter in addition to the rough terrain and Piercing damage, however all effects would only last 10 turns and the Piercing damage would drop to 1d4 after 5 turns. Came up with this with the players. I would say it is up to you still though.