x25 version has no credit price and both versions of the core are tagged as Limited-Rare eventhough it isn't limited.
8x -> RE: Piston Punch (9/1/2018 9:29:39)
No credit price is probably intentional, to have the same price as Bloodseeker Blast x25, Paralysis Coating x25, Mega Curse x25 and Mega Stun Blast x25.
The Limited tag is probably a bug. (Was about to report it before I noticed your thread)