Does Improved Divine Smite work in an Antimagic Field? [duplicate]

Question

At 11th level, a paladin gains Improved Divine Smite. This means (PHB p85):

you are so suffused with righteous might that all your melee weapon strikes carry divine power with them.

Given that the normal Divine Smite requires a spell slot to be expended, I took it to be considered as a spell and therefore unusable within an Antimagic Field (PHB, p213):

This area is divorced from the magical energy that suffuses the multiverse. Within the sphere, spells can’t be cast, summoned creatures disappear, and even magic items become mundane. [...] Spells and other magical effects, except those created by an artifact or a deity, are suppressed in the sphere and can’t protrude into it.

Improved Divine Smite, however, appears to be a quality innate to a paladin of 11th level or higher. Is it affected by an Antimagic Field?

Answer 1

Divine Smite is magical. Improved Divine Smite isn't.

Sage Advice Compendium contains an official ruling on how to determine if something is magical:

Is the breath weapon of a dragon magical?

Determining whether a game feature is magical is straightforward. Ask yourself these questions about the feature:

• Is it a magic item?
• Is it a spell? Or does it let you create the effects of a spell that’s mentioned in its description?
• Is it a spell attack?
• Is it fueled by the use of spell slots?*
• Does its description say it’s magical?

If your answer to any of those questions is yes, the feature is magical.

Improved Divine Smite fails all of the criteria. Divine Smite isn't a spell but it is fueled by spell slots, which makes it magical for rules purposes.

(When this ruling was first published in February 2016, it didn't contain the spell slot criteria. It was revised along with several others in August 2017.)

Answer 2

In conjunction with Slagmoth's answer:

The wording for Divine Smite (PHB p85) doesn't specifically indicate that is magical in any way, nor does the description of Spell Slot usage make it magical (PHB p201) thus it is not magical.

The fact that the original Divine Smite requires a spell slot is irrelevant and is merely a balancing mechanic limiting how often it can be done. Don't confuse having to expend a spell slot with the notion that Divine Smite in itself is a spell or spell effect. It is a passive mechanic meant to ramp up the base damage of the class.

To add further evidence, only one damage type (Force) is explicitly listed as directly tied to magic.

pg. 196 PHB

Force - Force is pure magical energy focsed into a damaging form. ...

whereas radiant damage is not

Radiant - Radiant damage, dealth by a cleric's flame strike spell or an angel's smiting weapon, sears the flesh like fire and overload's the spirit with power.

The angel's smiting weapon is similar to the paladin Divine Smite which should offer some insight.

Since radiant damage is not explicitly listed as a magical type of damage and the description itself doesn't specify that divine smite is magical, I would rule it is not considered magical and would be allowed inside an anti-magic field.

Answer 3

I would rule that the paladin's divine smite is an ability given to him by his deity, so it wouldn't be affected by antimagic field. I think because it is fueled by spell slots this is up for debate, but I see spell slots for a paladin just as a pool of divine magic that their deity gives to them every long rest. This is why I would think it would still function in an antimagic area.