Cyber Slash Harpie Lady has some of the strangest interruption effects in the game because it does not directly address the card it is responding to in the chain
Being able to protect your commander is invaluable, but you dont always want to play Lightning Greaves in decks where you might need to target your commander and you might not always need haste
Maybe it's just a Mewtwo thing
"Cubic Rebirth" was supposed to punish the opponent for declaring direct attacks by Special Summoning their other copies of the attacking monster from their hand, Deck, and Graveyard, then striping those monsters of all their ATK and placing Cubic Counters on them, but since Master Rule 4 this effect only enables the opponent to make high-Link Summons in their Main Phase 2
Not with a giant ugly stamp unless that is your thing, but with a custom back, a small proxy marker, or a visual treatment that makes the deck unambiguous