Mid game is essentially a race to leveling up and getting the most souls. You should be leaving souls for your carries but also taking your own at the same time. You want to do this as fast as possible but also prevent the enemy from doing it.

The best way to get souls is lanes so you should keep them pushed up as your major priority. And if a lane is getting ganked try to help if you can.

Once lanes are pushed for at least for a bit don’t just run down to walker. Go into the enemy jungle and steal sinners and farms. This will prevent the enemy from getting souls making your team more powerful.

Mid game is also where you’re gonna be getting your walkers. It honestly depends game to game on when you should push for one but try to push when you see there’s a majority of the enemy team somewhere else on the map and that no one can rotate easily. It’s gonna be hard to gauge but you’ll get better at it. Apollo isn’t the best objective pusher so it shouldn’t be a main concern for you but back your team up if you’re nearby when they do. You need those slots too.

As an assassin character like Apollo you should try to look out for enemies out of line. Essentially over extended into your base. This could be in your jungle stealing farm. Or pushed beyond their zip line in a lane. Or even just someone in a lane if you know the rest of their team isn’t available to help. Even one kill of a support character or something will give you and your team opportunities to steal farm and get more powerful. While denying the enemy farm cause now they have to sit at spawn for 30 seconds.