|I think Mel Taylor's the one who looks like he's from Lazy Town.|
Shoot The Curl
If you are rolling simple/phase initiative then the Surf Rockers roll a separate initiative. If you are running individual initiative then the Surf Rockers can instead Save vs. Spells, with a success meaning you go first and a failure just being your unmodifiable initiative roll. The name of the game is trying to go first, as you'll see below.
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Surf Rockers number at minimum a drummer, a guitarist, a bassist, and can include horns, keyboards, or 1-7 additional guitars. For simplicity's sake you are a four-person combo. You make decisions and investigate a mystery as a group, and if you are attacked then what hurts one of you hurts the band. Metaphorically. But I mean your hit points reduce. You almost never attack during normal combat but you can Waylay outside of combat if you have surprise on an enemy.
During a fight you can Rock A Gig to play gnarly surf music. This doesn't require spell components or slots or anything. It's just A) all you can do, and B) it requires the PLAYER to make surf music sounds with their mouth the entire time. Bowwdirdridwowdow gowwwgagiggabow bow duffe dududanan maaa ba gigga din dow.
While doing this and distracting all the other players, the Surf Rockers' player must pay close attention.
Write down everything that happens in a round that occurs AFTER/CONCURRENT TO the Surf Rocker's position in initiative. Every attack, movement, damage, spell, save, etc that other players and NPCs and monsters and shit make. KEEP MOUTH ROCKING or the effect wears off.
Once a round is finished, Surf Rockers can shut the hell up. They can now dictate the rhythm of the combat itself, determining what order everything happened/the order everything is resolved. Doing fuck all and being a hugggge target and BOWW GIGGA DOW DOW the whole time lets you, effectively, role play a character whose class is "Initiative."
Surf Rockers can Rock a Gig a number of times per day equal to their level.
Let's Split Up Gang
Surf Rockers who have Rocked a Gig are vulnerable and decidedly the center of attention. They double their movement and gain a Charisma bonus to hiding (their actual +1 or whatever from Charisma for d6, or their full Charisma score for d100) for the rest of combat.
Show Must Go On
Surf Rockers add their level to all saving throws during a combat.