When Lion’s Eye Diamond first entered the stage with the release of Mirage on October 1996, it was widely greeted with great disappointment. Wizards of the Coast had trolled players promising them a zero-cost artifact that could produce three mana of any color and until the card list was revealed, expectations for a Black Lotus reprint or at least something very similar were high.
Upon seeing that Lion's Eye Diamond required the player to discard their hand to actually get access to the promised three mana, many were simply disgusted and considered the card a useless bulk rare and a very bad joke. Brewers, however, did not give up on the card. Eventually, it did find some niche uses in conjunction with its place on the Reserved List, making its price rise slowly but steadily over the years.
Oddly enough, it took nearly two decades from its printing until the card seriously spiked, nearly doubling in price over a few weeks in early 2016 before once again stabilizing at its new level. Spiking once again later of the same year, the price took a dive followed by a steady decline until yet another spike in 2018 brought it up to around three times its pre-spike price! With the no reprint policy in place, the price of Lion’s Eye Diamond is expected to be on a steady increase, at least for the foreseeable future.
Lion’s Eye Diamond is a unique card with its own timing restrictions. It requires a build-around plus its player needs to pay attention to how it is played to fully benefit from it. In the right shell, the card is not only as strong as a Black Lotus, but it is a Black Lotus with an upside.
The card originally said: "Sacrifice Lion’s Eye Diamond, Discard your hand: Add three mana of any one color to your mana pool. Play this ability as a mana source." The current oracle's text is: "Discard your hand, Sacrifice Lion’s Eye Diamond: Add three mana of any one color. Activate this ability only any time you could cast an instant."
This correction means that Lion’s Eye Diamond cannot be used to cast spells from your hand in the usual way. But even though its ability can only be activated when an instant is allowed, it is still a mana ability which resolves right away – even if other effects are put on the stack after the Diamond is cracked.
One way to play Lion’s Eye Diamond is to hold priority when playing a tutor or wish effect and then crack it in response to get the mana without having to discard the card that was tutored or wished for. This is a popular choice in, for example, Bomberman decks. Using Karn, the Great Creator to bring a Mycosynth Lattice from your sideboard to your hand to activate Mycosynth's mana ability results in having the mana to already pay for half the expensive artifact. And in most cases, this will lock your opponent out of the game in combination with Karn’s static ability. In graveyard-based strategies such as dredge, activating the ability in response to drawing a card is an excellent way to get cards with the dredge ability from your hand into your graveyard.
Lion’s Eye Diamond is also played in decks such as Legacy Storm where Past in Flames lets you replay any discarded instants and sorceries using the mana from the artifact. In Vintage Storm, Yawgmoth's Will even lets you replay Lion’s Eye Diamond to double the mana yield. It is worth noting here, however, that the card is restricted in Vintage.
Whether it is because of its price or other factors, Lion’s Eye Diamond is only in 1.00% of all the Commander decks registered on EDHREC and one use in this format is in various cEDH Doomsday builds. Were it not for its price considered as too prohibitive, the percentage of decks including the card may well be higher due to the Commander 2019 deck, Merciless Rage, with its madness-based theme and Anje Falkenrath as commander. Lion’s Eye Diamond both delivers fast mana and a way to discard cards in order to cast them for their madness cost.