This effect is kinda an oddball even among the Duel Monster cards.
Shocklead Dragon
FIRE, Dragon/Effect, Lv 7, ATK 1600, DEF 2500
[Requirement] You can send the top card of your Deck to the GY.
[Effect] The face-up monster your opponent controls with the highest ATK (all of them, if tied) loses ATK equal to [the highest ATK among face-up monsters you control] until the end of this turn. This turn, this card cannot attack, except on Attack Position monsters.
