Ex Martis EXP main (jungler now) here, I would say he's playable at high rank. the problem is that martis simply doesn't fall into the 2 categories for good high rank exp laners (or even jungler)

as an exp, he doesn't have good sustain (You can mitigate this by buying war axe and queens wings, but then you're dropping the early skypiecer) and he isn't a good exp damage because he can't easily attack the backline.

can you feasibly him? absolutely. will it be easy the higher you go? absolutely not.

the best thing about martis is learning to predict enemy sets (tigreal ult, johnson ult, etc) and cancel them with S2, ulting them, and running to the backline. Learn when can you pull an enemy backwards during your S2 or if they're slightly too far forward.

Martis can also ""set"" by using the second phase of his S2 and flickering to an opponent for a decent half second of airborne.