# In RAW for 5e, can a player use a monster as a spell component?

One of the D&D legends stories that floated around my campus involved a poorly balanced boss fight in a 3.5 game. The players were facing a Giant Spider Wizard, and it was wiping the floor with them. A few rounds away from a TPK, the wizard in the party had an epiphany. He gathered several spell ingredients from fallen party members, then cast climb. The DM was confused and asked what the player did regarding the giant spider wizard. The player pointed out that casting climb consumed 1 spider, and declared that they'd used the boss as the spider.

Everyone agreed that it was too absurd and fun not to allow it, but that it probably violated the rules. (But hey-- half the fun of D&D is tweaking the rules to your preferences, right?) That being said, if someone tried that trick in 5e, per the RAW, would this work?

Almost all animals on materials components only say the animal's name, without stating if it must be alive or dead... with one exception. The Infestation spell requires a "living flea".

As per rules on Material Components:

Casting some Spells requires particular Objects, specified in parentheses in the component entry.

You could interpret this in one of two ways:

a) Having (living) in one animal means this is the only exception. The others are dead and treated as objects for this purpose.

b) Having (living) in one animal means the others can be either alive or dead. This would mean the description of material components being objects is a just a overlook on the writer's part.

Personally I believe a is the right one.

# If the monster could be used as component

Having spider as a component doesn't mean anything that resembles a spider can be used. A Giant Spider Wizard is not a Spider.

It's also important to remember that materials without a specified cost are not consumed unless the description says otherwise. So the spider wizard would not be consumed by the spell in the case of spider climb.

• Another interpretation is that the text is correct; i.e. a flea is an object, not a creature, as are spiders et. al. – Please stop being evil Dec 3 '19 at 17:04
• I agree with all, but I would also add that it is implicit that the material components be under the caster's control for use in the spell not just present in the room. Gathering monster components for exotic spells is a stock standard trope in RPGs including D&D. Using an actively fighting creature as a component goes against the implicit assumption that the caster controls the components. – TimothyAWiseman Dec 3 '19 at 17:37
• I think the key point that should be emphasized here is that materials without costs are not consumed. Otherwise the main points here are overly subjective. AFAIK neither the DMG nor the PHB have any explicit rules requiring components to be dead. Additionally I know of no ruling on the specificity of spell components, and most people would agree that a giant spider is a spider (though your point stands that a wizard is not necessarily a spider). Both of the main points in this answer are subjective arguments that the DM would have to decide. – Andrendire Dec 3 '19 at 21:06
• @CTWind the requirement of a "living" flea is simply adding a requirement to infestation's components. It's a vast assumption to insinuate that that single spell therefore establishes guidelines for every other spell in 5e. Just because hold person specifies that the target must be a humanoid does not automatically mean that all other spells can only be cast on non-humanoids. That's obviously a hasty generalization. – Andrendire Dec 4 '19 at 4:00
• @CTWind I'm simply illustrating how this answer's logic is fallacious. You cannot extrapolate that all components must be dead from the simple fact that a single component requires them to be living (a in A does not imply ~a not in A). Additionally--to answer your question--you can extrapolate, that a living creature qualifies as a object (it is listed as a component, and--by the block quoted text--a component is an object; a -> b -> c implies a -> c). – Andrendire Dec 4 '19 at 6:38

# No, the Giant Spider wouldn't be consumed.

But a DM could rule that use of the creature qualifies as one of the spell components.

The spell spider climb (PHB, 277) does have material components that are necessary for casting:

a drop of bitumen and a spider

But because none of those components are consumed, the use of a spellcasting focus or a component pouch(PHB, 203) removes the necessity of actually have those specific components.

A character can use a component pouch or a spellcasting focus (found in “Equipment”) in place of the components specified for a spell. But if a cost is indicated for a component, a character must have that specific component before he or she can cast the spell.

If a spell states that a material component is consumed by the spell, the caster must provide this component for each casting of the spell. A spellcaster must have a hand free to access a spell's material components -- or to hold a spellcasting focus -- but it can be the same hand that he or she uses to perform somatic components.

The components required for spider climb in 5e aren't consumed nor are they required to be eaten in a way that 3.5e required.

Because of that, using the creature as one of the components wouldn't actually destroy it because the spell doesn't require consumption of the component.

## Using the components

Let's say that your Wizard lost their pouch/focus. In this case, if they could find a drop of bitumen, they could absolutely use that.

The spider is a bit trickier. You aren't actually 'holding' the Giant Spider, so I'm not sure that qualifies as "hav[ing] that specific component." That bit is going to be up to the DM to rule on how they might achieve "having" the spider component.

Technically, the spell simply requires a spider. Is the creature you're fighting a spider? If so, then it's a viable component. It doesn't matter if it's a wizard or not. It matters whether or not it's a spider. It also doesn't specify live or dead, so there is no reason to require one or the other.

## Rule of Cool for using the Giant Spider as an unconsumed component

This DM (me) would look at a situation where a caster lost their focus/component pouch and realized that an enemy would supply a necessary component as clever thinking and reward it by allowing it. I'd still probably require them to be within 5' of the creature as a non-rolled 'touch' to cover the 'having' the component.

That doesn't necessarily help you beat the boss, though. Just allows you to cast a spell when you normally couldn't. I definitely wouldn't allow a caster to 'destroy' a creature by using it to cast a spell. That's too much of a gimme for me.