Every 3 shots the cluster bombs send out more cluster bombs for even more destruction.
Reclusive Cluster is the fourth upgrade of Path 3 for the Bomb Shooter in BTD6. It allows the Bomb Shooter to shoot tertiary bombs every third shot. That means that on every third shot, all 8 clusters will explode into 8 more clusters, totalling to 64 bombs on the third shot. It costs $2040 on Easy, $2,400 on Medium, $TBA on Hard, $TBA on Impoppable.