Tool didn't just cover Led Zeppelin's "No Quarter" on Halloween at the Monster Mash Music Festival in Tempe, Ariz. As you can see in the clip below, they dressed up as Robert Plant and company.

“Good news, it’s f--ing Halloween!" Maynard James Keenan reportedly said after the performance. "Bad news, we are not Led Zeppelin.”

Monster Mash is Tool's only announced tour date for 2015, and Keenan didn't sound all that excited about it in a pre-show talk with the Phoenix New Times – saying his bandmates in Tool "had to con me into it." Still, they put on a spirited performance of "No Quarter," in what was apparently the first time Tool played the Led Zeppelin song since 1998.

Tool also pulled out some of their own rare cuts – including "The Grudge" and "Parabola," which they hadn't performed with Keenan in years. In fact, the entire band hadn't shared a stage since March of 2014, though the rest of them reportedly appeared without Keenan at a VIP warm-up show in Tempe.

Maynard James Keenan has been performing instead with a separate comedic art-rock group called Puscifer, who just released Money Shot. He's also composing an authorized biography.

Tool's last new album dates back to 10,000 Days in 2006. "No Quarter" originally appeared on Led Zeppelin's Houses of the Holy in 1973.

Watch Tool Perform 'No Quarter' Dressed as Led Zeppelin

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