In a typical two-player game, when the combat phase arrives, the defending player is always your opponent (or one of your opponents in a multiplayer setting), and you cant declare yourself as a target of your own creatures
For players who are interested in collecting these mechanically unique cards without grabbing the rest of the cards, this is a great alternative
Pay enchanted creatures mana cost: Remove a net counter from this Aura
Magikarp has 30HP and once it has received damage equal to or in excess of this total, it will be Knocked-Out and placed in the players Discard pile along with any Energy or trainer cards attached to it
While the power level of this land is indeed high, and could perhaps be higher on the list if we just looked at pure power, I cant in good conscience put it any higher because its so easy to abuse
A literal win con for the deck