Combos allow for setting up dependencies between target shapes. This widely reduces the amount of otherwise necessary work with the node network and makes it easy to only drive correctives based on the state of other correctives under specific conditions.
Combos control the state of a target shape based on multiple sources, which can be either other target shapes or the combination of target shapes and the current driver for the shape.
Shape combos are easy to setup, even if the driving shapes are spread throughout the target shape list. Simply track your selection and create the combo after the last item.
The edit mode allows to add or remove driving targets at any point after creating the combo, as well as defining a different combo target.
When editing a bend shape target which is part of a combo, tweak propagation makes it possible to respect all related combo targets to maintain the visual appearance of all shapes.