There is a list of fluff prompts and a list of angst prompts. Each team picks one (from one of the lists), and turns it into the other genre, either turning a fluff prompt into angst or an angst prompt into fluff.

Here is the list that was used in this event: 

Angst

Lies

Goodbyes

Falling

Loneliness

Nothingness

Storm

Haunted

Arguments

Deny 

Frantic

Envious

Panic

Fluff 

Dancing

Miracle

Roses

Comfort

Confidence

Peace

Sunrise

Carnival

Celebration 

Stars

Protect

Blanket