Turns out I occasionally have ideas for cards. Thought I might post one. Putting it here because I'm not sure and it's about 5x easier than creating a proper card from my phone.
Deterioration (Spell)
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Halve target's effectiveness or efficiency.
For activated permanents (Mindgate) it doubles the cost to activate. Flooding is included here.
For passive permanents (Fog Shield) it halves their effect. A second use removes the effect completely. Shields which block an odd number of damage have a 50% chance to round up or down each attack.
Can target creatures. The cost of its active effect is doubled.
Not sure what happens to Owl's Eye.
This is essentially a counterpart to Reverse Time, except instead of reversing the target's time it's launched forward to where it is old and worn out.
EDIT: no idea if something similar's been done. Again, searching through archives isn't exactly easy at the moment.
EDIT 2: I'm a little worried that this is too boring and homogenising.