You cant sacrifice the same Clue both to draw a card and to pay the cost of another ability (like Lonis, Cryptozoologists, which lets you sac clues to steal cards from your opponent)
Ok Mega Darkrai ex #120 (Pokemon Pitch Black) Details All prices are the current market price
Those are good strategic answers, but if you already know what archetype you want to play, youre probably looking for a tactical answer, a sideboard card that lines up really well against this deck rather than a deck that you choose because it has a good matchup against Mono-Black Aggro, and I have some ideas
Add to this a handful of removal effects, card draw spells, and spells to pump your hydras even bigger, and you have a formidable deck
Its also worth knowing that unless you get rounded Ticket numbers from the bots, you wont be able to spend the remainder on other chains