stuck on fire division 10

Solar Vanguard has a gimmick like the other 4 division bosses, in this case you are not paying attention to the geysers, which spawn after dealing a chunk of the boss' health as damage, or not kiting the boss properly (that's not including the random blasts that also deal huge damage). Solar Vanguard has high damage output, but his attacks can be predictable if you know where, when and how to deal with them.

As an advice, you can use the Class Builds section in the forums to get yourself a new build, as Morph has been nerfed so many times that it is no longer a very effective solution to all content in the game.