 High entropy alloys, HEA, are metals composed of multiple elements, which have been shown to possess unique properties such as strength and ductility. In this study, researchers investigated the effect of certain parameters on the strength and ductility of these alloys. They found that a particular parameter, called kappa, was responsible for the strength and ductility of the alloys. This parameter was related to the number of close packed planes in the alloy, and it promoted the formation of different stacking sequences. These sequences were then linked to the strength and ductility of the alloys. The researchers used this information to design new alloys with improved strength and ductility. This article was authored by Zongru A Pei, Zhiting Zhao, Martin Detroi, and others.