Sentry Dash Boss [only rides in magma cube (big)]

a hardmode boss for my mod is a second vanilla boss, is called Sentry Dash or entity.SentryDash.name, this is a magma cube that rides another big magma cube Command: /summon minecraft:magma_cube ~ ~1 ~ {Size:3,Passengers:[{id:"minecraft:magma_cube",CustomName:"\"entity.SentryDash.name\"",CustomNameVisible:1,Size:10,Health:550,Attributes:[{Name:"generic.maxHealth",Base:550}]}]}