I don’t play Malene at all but here’s my take on it because I’ve been a witness/victim:
AC and AS are both items that have their own significance and both are AA dependent. Malene was the first case in a while ever besides old Vox where it was debatable if AC or AS should be built. The funny part is Malene is a spellcaster she shouldn’t use AS unless if she can get into AA range but that’s only safe to do if you have your empowered AA. AC is just stupid on Malene because it lacks crystal power, she doesn’t need attack speed, and well she already has a CP ratio on her AA. To be honest I never understood the controversy if it should be AS or AC. Both are inferior items on her.
SG does a lot of damage and she has pretty good CP ratios on her abilities, especially that light form A- which is that initial burst. CW is a must have because since she has multiple abilities to use a good Malene will stay active for a while and boom go back to literally doing nothing and then active again. And that is the jungle playstyle. With her upcoming cooldown nerfs she might actually be only viable in the jungle, and pretty damn viable at that.
Invasion wise, she is essentially a free kill onto the enemy team, especially with Glaive. One root boom dead. CP treant is good but you can get your top laner ahead by going with a 4man rotation onto the enemy red and by the time they realize this enemy bot and jungler get sandwiched in. Just hope that your bot laner has good clear though because it is up to him/her to clear fast and clear everything. This obviously required a certain extent of communication so either hope for the best or be on comm. Invading CP treant at this point should be meta in all tiers so I think its a basic invasion that I don’t really need to explain. This is kind of what gives Malene better performance in the jungle rather than the midlane because if I’m going to be honest most midlaners don’t both rotating when there is a river that gives them speedboost and such. You can play anything that can hypercarry in the midlane if you are good at rotating. Even Varya, a late game hero who literally doesn’t come online until late game, should be rotating.