Thematically I love the idea of summoning a giant ambivalent hand to chuck some dice around, it's a great idea. As you've mentioned, I think having presets is a good idea and gives you some space to think of situations where you need to change to particular presets at particlar times - like switching between a preset that blocks enemy projectiles and one that lets you jump across a gap or something like that. Looking forward to seeing what you come up with!