What is up with YGO and mind/body-control/possession?
You can only use 1 “Greydle Impact” effect per turn, and only once that turn. (1) You can target 1 other “Greydle” card you control and 1 card your opponent controls; destroy them. (2) During your End Phase: You can add 1 “Greydle” card from your Deck to your hand.
You can only use each effect of “Greydle Parasite” once per turn. (1) When an opponent’s monster attacks your directly, you can: If you control no monsters, Special Summon 1 “Greydle” monster from your Deck in Attack Position. (2) When a “Greydle” monster you control attacks directly: You can target 1 monster in your opponent’s Graveyard; if your opponent controls no monsters, Special Summon that monster to your opponent’s side of the field.