Sylas has 0.5 mr/lvl

why not?

because in order to have such a good ultimate his power has to be cut elsewhere so their options are on base stats or general kit

effectively they can have a really shitty baseline champion with a really cool non-ultimate kit or they can have the inverse to get who has such an underwhelming base kit because in balancing him for his ult power they nerfed the interesting parts of his kit into the ground.

like if you die to malz minions without having his ult on you you deserve to have died in that fight

so maybe making it so he can't just go full AP because he has to build defensively to an extent is a way to balance both that out and the dangers of having such a strong ult that scales with AP

Imagine him getting an ashe ult, or a GP ult with all of that AP, and his hijacked abilities also seem to adapt AD scaling to AP scaling, so imagine him with darius/pyke/urgot/zed/talon ultimates, or weirder yet if abilities scale with AP instead he could literally steal jayce's entire kit and just Q+E spam you with AP scaling Jayce damage.

So yeah he needs bad base stats, for the love of god force him to build somewhat defensively

They.. dont want to nerf the heal? perhaps?

he can copy a nasus ult or jax ult and hold onto it til his ult cd is back late game then proceed into a fight with a shit ton of health and resists. early on you won't see this but if games goes long enough sylas becomes a monster. this might be one reason why his magic resist is so low. that and he has one of the strongest self heals and shields in the game. he can easily shield for 1k and get back like 500-700 health from his w. not to mention copy chogath ults and get a shitton of free health. ( yes he keeps the health from chogath ult permanently ; yes its fcking strong )

Because he's not a midlaner.

He's an AP toplaner.

If you try to play him mid, you will get dunked on.