Swaps Hornet's crest every time she takes damage. Swaps Hornet's active crest with other unlocked crests or any other crest in the game (off by default, can be toggled in config menu). The mod ensures that the chest changes, so typically if you have two crests unlocked the crest will cycle between the two in a predictable way.
The loadout of each crest is per-crest, so you will alternate loadouts as you change crest when taking damage.
Configurable: You can toggle a Crest Sanity. It's on by default, in which case the mod will swap only with other unlocked crests. If you turn it off, ANY other crest in the game can be selected, whether that be Shaman, Cloakless, Cursed, or any of the Hunter Crest evolutions (which, yes, are separate crests internally). Use this at your own risk, if you only want pure chaos.