This stage will immediately bring fire stages from the Mega Man days of yore to mind. And its level of challenge is right up there, too.
For the most part this is a straightforward level, but an all-out challenger. There are some giant flame dispensing units in areas in the level, and one hit from these will kill you outright. So steer clear. If you got the Concrete Shot already, it can freeze them.
A frustrating Dragon miniboss is battled about halfway through the level. He soars across the screen and leaves, raining down fire as he does so. Use Black Hole Bomb on his front has he first starts flying by to suck up all the fire and deal harm to him. Tornado Blow works even better (you don't even have to aim), but you want to save that for the boss.
Eventually you'll arrive at Magma Man's domain (doesn't he look like a red Needle Man?) Immediately start shelling out the Tornado Blow. You'll run out of it quickly, but damage him severely in the process. From there on out, simply finish him off with whatever other weapons you have that work best. His main attack is with three-way fireballs, but these aren't too tough to avoid. The shape of the arena is strange, but can work to your advantage if you know what you're doing.
A victory will earn you the Magma Shot. This fires fireballs in a "three way" pattern like Magma Man himself, plus it can be charged and fired for more damage.
If you started with Galaxy Man, this will be your fifth victory over a Robot Master - so you'll earn the Rush Jet.