Arachnus Web

A pacifism effect with a built-in expiration clock, and the clock is the whole design conversation. Standard Pacifism shuts a creature off permanently for two mana; this asks for an extra green and then hands a window back to the opponent. Anything with power 4 or greater shrugs the Aura off at the next end step, so the lockdown only holds against small and midsized threats. That conditional destruction reframes how the card is sequenced: pin down a 2/2 or a 3/3 and it stays pinned, but try to neutralize a fattie and you have spent three mana to buy one turn, because the Aura self-destructs before that creature attacks again. The wrinkle is that the power check happens at end-step resolution, which means a creature pumped past 4 only on your opponent's turn (a +1/+1 counter, an equipment, a one-shot buff) can trip the trigger and free itself. It also disables activated abilities, a quieter clause that matters against mana creatures and pingers whose threat has nothing to do with combat. The result is a removal-adjacent answer deliberately tuned to fail against exactly the creatures you most want to stop, which is the cost green pays for being allowed to deal with a problem permanent at all.