Rainbow Substance is an odd rainbow liquid vomited by the Puffball species in times of stress. It was first seen in BFDIA 4 after Puffball stated how she hopes Dream Island will be found, which causes her to vomit the substance. It was used twice in BFDIA 5a by Puffball when she found out that her speaker box got stabbed by Pin and Puffball Speaker Box when she died. Its last appearance was in BFB 12, when Rocky, inside of Puffball's body, threw it up due to his chronic vomiting issue. The substance looks somewhat similar to the Twinkle of Contagion.