The card is responsible for most turn one wins and is a total game changer. When using Lion’s Eye Diamond it's crucial to know that you must maintain priority and activate it in response to your other spell before passing priority/checking to see if there are any responses. When using Lion’s Eye Diamond paired with Infernal Tutor, it's important to note that you can cast Infernal Tutor with a card in hand and then use Lion’s Eye Diamond to become hellbent by activating the artifact.
Try to cast Lion's Eye Diamond at opportune times, I play this card very differently depending on the match-up. Sometimes I let it sit on the table and threaten the opponent – while in other situations I hide it in my hand or on top of my deck. I typically play it right before my Infernal Tutor or Burning Wish, to maintain priority, this way it cannot be destroyed by effects like Abrupt Decay or Kolaghan's Command.