Myriad is a cryptocurrency that supports 5 algorithms, catering for ASIC, GPU and CPU mining. Currently, those algorithms consist of SHA256d, Scrypt, Myr-Groestl, Argon2d, and Yescrypt. Myriad's multi-algorithm approach offers 51% attack resistance as a range of different hardware would be needed to find 51% of the blocks. Merge mining is available on the SHA256d and Scrypt algorithms, enabling Myriad to take advantage of the hashrates used by the coins leveraging these algorithms (BTC, LTC)
More information can be found at http://myriadcoin.org/.