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)?


3 Answers 3


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.


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.


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