Both Starkad and Poseidon are hash functions based on a new design strategy called Hades. In contrast to classical SPN ciphers (e.g., Shark) and partial SPN (P-SPN) ciphers (e.g., LowMC), Hades makes use of rounds applying the nonlinear transformation to the whole state and rounds applying it to part of the state. The main idea of this approach is to facilitate cryptanalysis regarding statistical attacks, while at the same time reducing the total number of expensive operations in the target use cases.