On Halloween, rock and metal fans were treated to one of 2015's most anticipated shows. The headliners were Tool, who played their only show of the year to a sold-out crowd of 30,000 in Tempe, Ariz.

On a beautiful, cloudless day in a city within the middle of the Arizona desert, the crowd settled in early to watch a full day of music. First up were Arizona natives With Our Arms to the Sun, who proved to have one of the day's most memorable sets. The 20,000+ fans already inside the festival grounds immediately after gates opened were soaked in the cinematic act's unique blend of metal and psychedelia. Opening bands, especially at Tool shows, will regularly be greeted with hostility or indifference, but With Our Arms to the Sun kept fans engaged from the first note to the last.

Los Angeles rock act Aeges kept masked heads bobbing as the sun began descending, just before Coheed & Cambria performed to the massive crowd. Coheed & Cambria fans are incredibly diehard, as evidenced by audience's overall reaction to the band's career-spanning set, which featured four tracks from the recently released 2015 full-length, The Color Before the Sun.

Primus were next to take the Monster Mash stage, and though they didn't seem quite as energetic as they have in the past, Primus' one-of-a-kind style left Tempe hypnotized. Accompanied by giant mushrooms on both sides of the stage and background video suited for public access television at 3AM, Primus gave fans a set of hits including "My Name is Mud" and "Jerry Was a Race Car Driver."

Tool fans came from all around to see the cult band perform its only 2015 gig, and if you took a plane to Arizona like we did, it was plain to see who was headed to the desert for music. Halloween brought out some innovative costumes to the fest, including multiple fans dressing as the boy from Tool's "Hooker With a Penis." You can paint your own picture.

Tool joined the crowd in celebrating Halloween, dressing as Led Zeppelin and kicking their set off with their celebrated cover of "No Quarter." Guitarist Adam Jones even busted out a red double-neck Gibson SG just like Jimmy Page. Tool surprised the crowd yet again by unleashing "The Grudge," which hadn't been performed live since 2002. Though Maynard Keenan opted out of the track's signature scream, the treat was extremely appreciated.

The 13-song set included extended versions of "Opiate" and "Schism," a drum solo from the mind-blowing Danny Carey and an instrumental jam of "Descending," which seems to be one of Tool's new songs from their ridiculously anticipated next album. Tool closed out the night with an extended jam of "Stinkfist," bringing Halloween night to a close in Arizona.

Check out exclusive photos from Monster Mash Day 1 in the gallery above. (Tool did not allow photography of their set.)

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