How can I spend the mana from Lion's Eye Diamond?

Question

With this question, I would like to shed some light on the Lion's Eye Diamond card, and some of its possible uses. It is an incredible card, which in some ways is similar to the Black Lotus, but which unfortunately cannot be completely associated with it, for obvious reasons.

First, it is possible to note that the Oracle card text and the original card text are noticeably different. At first glance, it would seem that the only current use for this card is the ability to use the three mana for some activated ability of the cards that are already in play.

In fact, I think I can exclude the possibility of "starting to cast a spell". With this last expression, I mean in the sense that, having chosen a spell from the hand, and with the Diamond already on the battlefield, you can cast it thus excluding it from the hand – and thus sidestepping this way the wording "discard your hand" as regards the spell you would cast with the help of the Diamond.

In other words, I don't think it's possible to use this card as a mana source anymore, and with the rules associated with mana sources only: this is also because, unlike the original text, Oracle says that the ability of this card can now only be played as an instant.

But even this use seems really strange to me ... Before the errata, it was a mana source, and now, even if it remains largely such, it must be used as an instant ... There remains, in my opinion, no other possibility of using this card for the activated abilities of the cards already in play.

I would want to know if what is reported here is correct, and if any expert – or, who has ever played with this card – has any idea how it can be used differently from the way shown here.

Answer 1

Lion's Eye Diamond was not errataed to make it harder to use, it was errataed to maintain its original functionality

Lion's Eye Diamond is old. It was printed in Mirage, which was released in 1996, only three years after Magic was first printed. As such, it predates the Sixth Edition Rules, the largest rules revamp Magic has ever seen. The Sixth Editions Rules restructured how a turn works, implemented the stack (replacing a previous concept of spell resolution called "batching"), and notably for our purposes, changed when you were allowed to get mana.

Before the Sixth Edition Rules, you had to have your mana available before you started to cast a spell. But the Sixth Edition Rules created mana abilities which did not use the stack, and could be used during casting when you are asked to pay for mana (Mana Sources, like Lion's Eye Diamond's ability were not what mana abilities are now. They acted more like instants that produce mana).

The intention of Lion's Eye Diamond was to force you to discard your hand before getting the mana, so that you couldn't use the mana to cast spells. The Sixth Edition Rules made it possible to use LED while a spell was already in the process of being cast, circumventing that intention. So LED was given errata that required it to be cast at instant speed, returning it to its original functionality.

Answer 2

Yes, you're right, you cannot use Lion's Eye Diamond to cast spells which are currently in your hand. The rulings below the card even admit that it's a strange one:

The ability is a mana ability, so it is activated and resolves as a mana ability, but it can only be activated at times when you can cast an instant. Yes, this is a bit weird.

Other than activated abilities, or decks who want their graveyards to be filled (e.g. for Bridge from Below, another card which Gatherer admits is a bit weird.) and care less about the hand, there are some exceptions: most notably cards with Madness or Flashback. In both cases, you can just activate the Diamond, causing you to discard your hand. A card with Madness can be cast for its Madness cost because it's being discarded; a card with Flashback because it's now in your graveyard.

Answer 3

If you have a LED on the field and a card you want to cast in your hand, you cannot cast it using LED's mana, as Glorfindel points out.

However, you can still draw cards after the LED ability resolves, and use the floating mana to cast the spells. You can for example pay 2U (using lands, not LED) to cast Divination from your hand, hold priority (not resolving the Divination), crack LED, discarding the rest of your hand, now let Divination resolve (if your opponent allows it of course), draw two cards, and use the three floating mana from LED to cast a spell you just drew.

Notably, the famous Storm deck for legacy runs the combo of Infernal Tutor with LED. If you do the steps above but using the Tutor instead of Divination, the Hellbent ability will always trigger, letting you pick any card from your deck (e.g. Brain Freeze or Grapeshot if they can finish the game on spot) and cast it using LED-produced mana.

Answer 4

Glorfindel mentioned Madness and Flashback, and Mephy mentioned using it while a card draw effect is on the stack. There are a few more ways to use it:

Have a permanent that allows you to draw cards. For instance, if you have Alchemist's Apprentice on the battlefield, you can sacrifice LED, then sacrifice Alchemist's Apprentice to get another card that you can cast.

Cast cards from your library. For instance, Elsha of the Infinite allows you to cast the top card of your library.

Cast cards from exile. For instance, you can cast Act on Impulse, sacrifice LED, then cast one of the cards you exiled with Act on Impulse.

I believe that you can also use it during your upkeep. So you could pay upkeep costs, or you could do something like cast Slaughter Pact, then during your next upkeep sacrifice LED to pay the 2B. This would let you use any Pact regardless of whether you have lands that produce the correct color of mana.