The_Librarian says:
I'm definitely going for the shadowy sneaky idea, striking from being hidden. I was considering the darkness sphere.
The darkness sphere has two uses: sneaky stuff, and battlefield control. By which I mean: creating darkness can allow you to use said darkness to hide, or to teleport around (shadow jump), or to improve your dastardly maneuvers thanks to the talent Tenebrous Legerdemain, so yeah, if you want to take a class that blends spherecasting with martial abilities, and use it to create what essentially is a magical rogue on steroids, then that's definitely one way to go. The end result would be something similar to Violetta and the Smoke Knights, if you've ever read the webcomic Girl Genius. If you haven't read Girl Genius, then just imagine a rogue mixed with a shadowdancer (the pathfinder prestige class).
However, the darkness sphere can also excel at battlefield control: it can use the enemy's shadow to pin them to the ground and prevent their movement, it can transform an area of darkness into a pool of shadowy liquid so that the enemy will drown in it, it can lower the enemy's saves, it can be mixed with the telekinesis sphere to create literal black holes. Or heck, you can mix it with the war sphere, creating areas that will buff your allies while simultaneously debuffing your enemies, essentially turning you into a traditional zoner: you mark certain zones of the battlefield, and then decide what happens inside those zones.
In general, the wider the uses of your powers, the more you tend to be pushed into a control/support role: traditionally, such a role is better left to the most experienced players at the table, as it requires minute knowledge of many moving parts which might fly right over the head of the newcomers... And with Yamazaki playing a tank, it looks like the control/support role is going to fall at my feet, either with the Herrscher concept I detailed earlier, or with something else entirely (either way, it seems like the more offensive Daybreak concept is off the table for the time being, as attacking with weapons, being a more straightforward way of dealing damage, is better left for the newcomers). So yeah, of the two uses of the darkness sphere I have described I honestly recommend you stick with the first one, as the second one would probably be a bit too complex for you.
Does this make sense? If so I will suggest some potential classes next.