Karvish, Dark Reclaimer

Whenever an opponent attacks you or a planeswalker you control with one or more creatures, create a colorless Treasure artifact
token with "{t}, Sacrifice this artifact: Add one mana of any color."
{2}{b}{u}, Sacrifice X Treasures: Plunder X (To plunder X, gain control of target nonland permanent with converted mana cost X or less.)
"Welcome to the crew."