Knockdown, stun, frozen, petrified.
Aside from it not really being all that great for there to be that many effects that function identically, it's also essentially stifling most strategies that don't take advantage of permanently locking the enemies out of acting.
Hence, it would be most beneficial if said effects were changed to achieve their goal in different ways, and at a more manageable magnitude.
For example:
Knockdown: The target spends a number of AP proportionate to the duration of the effect to stand up. Afterwards the effect is removed and they act normally.
Stun: The target does not recover their normal AP amount at the beginning of the turn. If they have AP saved, or some other means of recovering it, they can use those as normal.
Shocked(alternative Stun): All actions taken by the target require 1 additional Action Point to perform.
Frozen: Target gains <magnitude> barrier, that absorbs all damage and cannot act until the barrier is broken or the effect ends.
Petrified: Target cannot move or act, and is immune to magic damage.
