A Lasso can be thrown at forest creatures to catch them. While attached, a stamina bar appears over the mob's head. When the bar reaches 20%[Confirm], a prompt to reel appears. Right-clicking depletes the stamina bar and pulls the mob in. If the mob has multiple layers to its stamina bar, it instead removes 1 layer and needs to have the process repeated again.
A Lasso can detach from a mob by reeling in too early, looking away, or not reeling in time. This allows the mob to regenerate its stamina.