"Magnets" is an electronica and dancehall song with influences of reggae fusion along with electronic beats, percussion loops, synthesizers and tribal drums in its instrumentation.

[7] "Magnets" is described as an atmospheric dancehall[8] and electronica[9] song with influences of reggae fusion[10][9] along electronic beats,[11] percussion loops,[12] synthesizers,[12] and tribal drums in its instrumentation.

"[14] Disclosure teased the song in an interview with Spin, who described the writing process as a proper collaboration, from the "drum sounds to the chords".

They stated that Lorde was involved with "every aspect of the song" as opposed to doing the "lyrics and melodies" and then leaving the rest for the duo to finish.

"[12] Pretty Much Amazing writer Austin Reed said the song could serve as a "pop music blueprint" and praised its "light and whimsical."

"[15] Sharing similar opinions, Consequence of Sound called the duo and Lorde's musical chemistry as "stronger than ever" and praised the singer's "soulful vocals".

Club praised Lorde's "signature catch-in-throat voice teases and taunts on the [song's] hiccuped rhythms,"[17] while The Guardian highlighted the singer's slinky playfulness on the track.

[21] Sharing similar sentiments, The Guardian stated that while Lorde provides "spidery vocals", the singer "sounds aloof to the point of boredom.

"[22] Rolling Stone ranked "Magnets" at number 32 on its year-end list to find the 50 best songs of 2015, calling it "the year's most understated dance-world magic".

[26] "Magnets" was one of several songs to crossover to rock airplay without rock-focused guests, including Avicii's "Wake Me Up" (2013) and Daft Punk's "Get Lucky" (2013).

"Magnets" was voted in at number 10 in Australian alternative youth radio station Triple J's Hottest 100 countdown of 2015's most popular songs, announced on 26 January 2016.

Some of the outfits used included latex Dior boots, a Rona Pfeiffer arresting swallow necklace, and a cream gown from Michael Costello.

[30] Its visuals and storyline were praised; the style of Lorde's femme fatale character received comparisons to Trinity from The Matrix film series (1999–) and the White Witch from The Chronicles of Narnia (2005–2010).

"[38] In an analysis from The Atlantic, writer Spencer Kornhaber stated that the music video was part of a trend of women performing acts of violence towards other people.

Rolling Stone stated that the "drumline-enhanced performance also featured a brief tribute to Paris," who experienced a terrorist attack the prior day.

[42] The Fader stated that the performance benefited from the "extra musicians, with the sampled hits being supplemented by live marching drums.

"[43] Idolator described Lorde's look as being an all-black dress with a "shorter haircut and blood-red eyeshadow" which fully embraced the "vengeful and sultry vibe found" in the video and song.