The Mage Slayer feat provides the following benefit, amongst others:

You have advantage on saving throws against spells cast by creatures within 5 feet of you.

For spells with a duration of instantaneous, it's clear when this effect occurs - when the creature is within 5 feet of you, and casts a spell you need to make a saving throw against.

What about spells with longer durations, where the casting and you making the save might not be at the same moment? Examples might be Evard's Black Tentacles, or Thunderous Smite. Does the creature need to be within 5 feet of you (a) when they cast the spell, or (b) when you make the saving throw (or both)?


4 Answers 4


RAW indicates that 'b' is correct.

It says 'cast by', not 'cast by when you were' or some such. Ergo, by the wording, you get advantage on saves against any spell you are affected by (instantaneous or no) while the creature that cast that spell is within 5'. That means if you were making a save each round against a spell, if your teammates grabbed the spellcaster and dragged them over next to you, your next save would get advantage.

Rules-As-Intended, it's unlikely that the designers thought much about advantage on longer-term effects. The ability seems more like 'the spellcaster tries to shoot you with a spell while you're up in their face and you get a greater chance to resist or dodge it due to being up in their face'. But it's unlikely that there would be greater favour for the 'you were standing next to the Evil Shaman when he cast that poisonous fog, so for the rest of time you are able to resist that poisonous fog better even after the shaman teleports home' reading amongst the designers than for one where when the shaman creates fog around himself you are better at resisting it if you're standing next to him. Neither makes a huge amount of sense, but the latter seems more in line with the intended effect of the feat.


RAW is unclear, so DM decides.

The rule text can mean several things, at least these:

You have advantage on saving throws against spells cast by creatures, when the spell is cast within 5 feet of you.


You have advantage on saving throws against spells cast by creatures, when you make the saving throw within 5 feet of the creature that cast it.

Which one is correct can be argued based on flavor and intention of the feat, as well as nuances of English language, but there is no clear, non-disputable correct interpretation.


The Grammar is Inconclusive

As you, and other answers, say, the grammar of the initial phrase is indeterminate. It could mean the caster needs to be within five feet of you when the spell is cast, when the save is made, or both.

The Feat is Inconsistent

One way to attempt to find RAI is to look at the other parts of the Feat as a cohesive whole. The saving throw effect is the third of three benefits. What do the others say? Well, the first says:

When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature.

This part specifically ties the benefit to the action of spell-casting within five feet. It is thus tempting to think that all of the benefits flow from that. After all, the feat is introduced as:

You have practiced techniques in melee combat against spellcasters,

However, this falls apart when one considers the second benefit,

When you damage a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration

and realizes that it has nothing specifically to do with melee combat. As written, even ranged damage you do to the caster counts for this benefit. If the second benefit doesn't match the feat's introduction, we can hardly expect the first benefit to help us interpret the third.

The Lore is Unhelpful

Another potential source of RAI is to look at how the Feat worked in previous editions. For example, in 3.5 it was described as:

You have studied the ways and weaknesses of spellcasters and can time your attacks and defenses against them expertly... Benefit: You gain a +1 bonus on Will saving throws. Spellcasters you threaten may not cast defensively (they automatically fail their Concentration checks to do so), but they are aware that they cannot cast defensively while being threatened by a character with this feat.

Here we see that while the spell-disruptive function clearly takes place in melee, the benefit to the save is not tied to caster proximity at any point. That is no help either.

A narrative approach (what I would do)

What is a Saving Throw?

The benefit of interest to you is advantage on a saving throw. A saving throw:

represents an attempt to resist a spell, a trap, a poison, a disease, or a similar threat...A saving throw can be modified by a situational bonus or penalty and can be affected by advantage and disadvantage, as determined by the DM.

Thus, the purpose of the third benefit of the feat is to make you better at your attempt to resist the power of the spell. What situational bonus would make you better at resisting a spell's power - threatening the caster when they cast the spell, or when you make your save?

Threatening the caster weakens the effect of the spell on you

In 5e, spellcasters invest power in the spell when casting, always. It makes good narrative sense for their spell to have less effect on you if you could threaten them when they were casting it.

Spellcasters sometimes continue to provide power or focus to a spell after it is cast - these types of spells require Concentration. Other spells with lasting effects require no further input from the caster - once cast successfully they are completely independent entities, and casters cannot even end them if desired. If the power of the Feat comes from weakening the spell by threatening the caster, it makes narrative sense (at least to me) that advantage to the save would be granted to any spell where the caster was within five feet of you when the spell was cast, always, and within five feet of you when you made the save, only if the spell required Concentration. If hitting (or even killing) the caster would not weaken the spell, having the caster within five feet of you when you made your save should not make a difference in your ability to resist it.

Note that some spells with delayed saves, such as web, do require Concentration, while others, such as grease, do not.

This is one possible narrative interpretation - that the spell itself is weaker because your proximity to the caster disrupts it. It is certainly not the only possibility. For example, "maybe it's the hatred that fuels you" suggests that it is not that the spell itself is weaker, but rather that your will to resist it is stronger when the caster is in proximity to you. Given that all the other approaches to determining the intent of the spell are inconclusive, I recommend the narrative approach - but a narrative approach that makes sense to you as a DM in terms of your assumptions about how magic works in your world.


RAW indicates that ‘a’ is correct

Spells are “cast by” creatures at a particular time. At that time, they are either within 5 feet or you or they aren’t.

  • \$\begingroup\$ Saving throws are are made against spells at a particular time. At that time, the caster of the spell is either within 5 feet of you or they aren't. For the record, I do think (a) is correct, but grammatical parsing won't get you there. \$\endgroup\$
    – Kirt
    Commented Feb 21, 2023 at 5:08

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