This add-on adds two major lattice-based deformation tools as well as some minor additional utilities for lattices to Blender.

Documentation can be found here.

Tweak Lattice

This tool lets you quickly deform a set of mesh objects, similar to Proportional Editing. Except instead of just a fire-and-forget operation, this is done with an object in 3D space, which can be parented to your deforming character, follow their armature deformation, and be animated!

Camera Lattice

This tool lets you deform a collection of objects from a particular camera perspective, essentially like Liquify, except it's operating on vertices instead of pixels. Although lattice points cannot be animated, the add-on provides a workflow for easily managing a set of shapekeys and their keyframes, to help you work with this liquification in an animation.

Both tools were designed to be used for character animation tweaks in a production environment, and so they fully work with linked and overridden animated characters.