How To Stop Creatures From Flying?
If you Freeze Time, layer two Prismatic Spheres above a monster, and then cast Reverse Gravity, you can shove them through 4 layers of Prismatic Wall and force 28 separate saving throws. But this is completely dependent on the target creature not having a Fly speed, which limits this strategy to very few creatures at the high levels where it's viable. At the levels where this combo exists, what are our options for negating Fly speeds so they can get launched by Reverse Gravity?
Many spells and effects designed to prevent flying like Earthbind prevent the creature from leaving the ground in any way, so that might also stop them from being getting launched by Reverse Gravity. The Runesmith's level 17 rune of binding can reduce Fly speeds by 40 feet, and negate them entirely if this reduces them to 0, but at this point most monsters are much faster fliers than that.