Yu-Gi-Oh! 10 Powerful Cards So Good They Were Banned!

Topologic is a Rank 4 which required any 2 or more special summoned monsters. If a monster was special summoned to any linked zone during either players turn you could discard up to 2 random cards from your hand which forced your opponent to discard 2 cards too. Then, during your turn, if it is in your extra link, you can make your opponent discard up to 2 more cards and burn for 3000 damage if they have no cards after this.

The card was relatively easy to summon with enough synergy but it's ability to wipe out an opponents hand lead to some truly brutal combos if going first. The card was very splashable but saw competitive play in Hero decks that made use of Malicious and Phantom Knights to gain advantage on discarding and could search out Neo-Spacians using Connector.

Summoning Aqua Dolphin allowed you to discard to destroy a card in your opponents hand, and with Gumblar, forced your opponent to consistently discard their entire hand to the graveyard, before they even had a chance to play the game. This left them with only 1 card on their opening hand, which would leave them defenseless basically guaranteeing a win if played first.