Here's why:
* Tribute Summoning: Tribute summoning requires you to send monsters from your own field to the Graveyard as a cost to summon a monster from your hand.
* The Wicked Avatar: This monster's summoning requirements are specific. It requires you to send two "Wicked" monsters from your hand or field to the Graveyard.
Important Note: You cannot tribute opponent's monsters as part of summoning conditions for any monster in Yu-Gi-Oh! Tribute summoning only works with your own monsters.
Additional Information:
* "The Wicked Avatar" can be summoned using an opponent's monster: If you can successfully use a card effect or spell to send an opponent's monster to the graveyard, you can use those monsters to summon "The Wicked Avatar" as long as you also send two "Wicked" monsters to the Graveyard. However, this is not a direct tribute summon.
Let me know if you have any other questions!