Imagine Dragons rocked Caesars Palace in a charitable way on Aug. 25. The Las Vegas band held its fourth annual Tyler Robinson Foundation gala, emceed by actor Joel McHale. The event drew 700 attendees, more than double the turnout for its first event in 2014 at Hard Rock Hotel.

A little more than $1 million was raised through table donations and the event’s live and select auctions. Tyler Robinson Foundation is a childhood cancer support and treatment organization named in honor of a young fan who befriended the band (mostly through text chats with frontman Dan Reynolds) who died of a brain tumor in March 2013 at age 17.

Highlighting the event, Imagine Dragons performed an acoustic set peppered with its best-known songs, including, “It’s Time,” the song dedicated to Robinson; “Shots,” “I Bet My Life,” “Amsterdamn” and “Radioactive.” Reynolds also summoned star guest Paul Shaffer of the World’s Most Dangerous Band on David Letterman’s talk show for a run through “Stand By Me.”

Photos by Denise Truscello/WireImage