It's alters the cap permanently, not for 3 turns. Just the effect of reducing your cap with quanta use is for 3 turns.
while it is fine to reduce the cap permanently,
how long does the effect that causes the cap to be reduced last?
thats right, also permanently.
thus, this will require a symbol alike silence/nova/sanctuary
which all last a limited time (or are a permanent).
As like S. cat, Antimatter, Fractal... And if it was easy to lock up your opponent, it will be OP.
This is not comparable to cats, antimatter, or fractal:
cats and fractal do not counter the opponent's strategy, they are based on your own.
antimatter does counter the opponent's strategy, but it counters a wide variety of strategies.
this is more comparable to flooding, which basically counters creature spams.