One of the benefits of the Shield Master feat in 5e (PHB, p. 170) reads:
If you aren't incapacitated, you can add your shield's AC bonus to any Dexterity saving throw you make against a spell or other harmful effect that targets only you.
Though it's pretty clear which spells it's useful against (spoiler: not many), I'm still puzzled about what other harmful effects it can be helpful to protect from.
If I read the rule literally, it turns out, that I can't benefit from this bonus against an avalanche (because it's an AoE), but I can use it against getting into a hunting trap, that honestly doesn't have anything to do with whether I have a shield or not, which seems absolutely counter-intuitive.
My question basically consists of two parts:
- Do I understand RAW correctly? (For instance, maybe there is a narrow definition of "harmful effects" somewhere, that I don't know about.)
- What are the guidelines (preferably with examples) to determine, whether Shield Master feat gives a bonus against a certain harmful effect.
Best Answer
Harmful Effects Defined
The term "Harmful Effects" is not actually defined by 5E, even though they use the term in several places. The closest we get to a definition is this:
Damage Types
so we go with the plain English definition. Harmful means:
And Harm is defined as:
Thus, we can conclude that "Harmful Effects" speaks specifically of things that can damage you. In short, by a strict usage of the English Language--that Shield Master feature applies against effects that...
This meshes with the Damage Types statement linked above, as it talks about Harmful Effects dealing types of damage.
Specific Examples
I'm pulling all of these from Class Features, as they are the easiest to search
Feature works against
These class features meet all three criteria: They only target one person, require a Dex Save, and deal damage.
Storm Herald Barbarian's Storm Aura, Sea Option
Tempest Cleric's Wrath of the Storm
Arcane Archer's Seeking Arrow
Monk, Way of Four elements: Water Whip
Feature does not work against
In both of these examples, you are making a Dexterity Save to evade an effect that doesn't deal damage. Thus, the Shield Master feature does not aid you here.
Way of the Open Hand: Open Hand Technique
Paladin Oath of the Ancients, Nature's Wrath