(I used sentry cannons for all bosses)

For the first boss I focused on the ship, i tried to reflect all the projectiles.

For the second boss I focused on the big claw first then i would roll to the fire thing. For the second faze I had both of my cannons on the top of the ship while I focused on the claws, doing the same strategy as before but with more rolling.

For the third boss I focused on dodging the stun beam thing then I would take out the fire thing. When they got close i would first take out the fire thing then go to the closest one then I would roll to the next one. (this would be while my cannons on there respected side are firing).

For the first times I beat the finale boss I would get a artifact (preferably the ship(+3 HP), the shell(+30% cannon damage), or the barracuda(+30% cannon fire rate) then I would double it and I would take over the sentry cannons to hit the boss more.

Hopes this helps, I don't think it will but I hope it does.