The Lost Caverns of Ixalan (LCI) was Magic's take on the "Underground World" trope, interweaving themes of exploration and discovery.

One of the most memorable Keyword Abilities from the set is Discover, a built in two-for-one on spells cast with this mechanic. It sounds powerful, but exactly how does it work?

How Discover Works

The Reminder Text on Discover is lengthy but it explains the ability in complete detail.

"Discover N: Exile cards from the top of your library until you Exile a nonland card with mana value N or less. You may cast it without paying its mana cost if the resulting spell's mana value is less than or equal to N. If you don't cast it, put it into your hand. Put the remaining Exiled cards on the bottom of your library in a random order."

To break this rule down, let's take a closer look at a specific card.

Geological Appraiser is about as simple as it comes when it comes to the Discover ability. For four mana, you summon a 3/2 Human Artificer Creature that enters and (assuming you cast it) triggers Discover 3.

When the Discover Ability resolves, you Exile cards one at a time from the top of your library until you find a nonland card with mana value three or less.

At that point, you are faced with a decision. You can either cast that card without paying its mana cost, putting it directly onto the stack, or you can put it in your hand. Any of the cards you passed by because they were Lands or cost more than three mana then get shuffled together and placed on the bottom of your library.

In this way, Discover is a powerful, value generating machine. In the case of Geological Appraiser, you get your 3/2 Creature and whatever spell it Discovers, and it even offers to pay the mana for that spell if you're interested in casting it at that moment.

Rulings You Should Know

In practice, Discover functions intuitively. After you see the ability resolve once or twice, you'll be comfortable resolving it at your next FNM. However, there are some important rules associated with the Keyword Action that you should understand in case an opponent starts asking questions, especially if they didn't play during LCI.

• A spell's mana value is determined only by its mana cost. Anything that alters costs (e.g., Sphere of Resistance or Trinisphere) is ignored in the calculation, but you must pay mandatory additional costs if you wish to cast the Discovered spell.
• When you Discover, you must Exile cards. That's not an option. The only decision you make is whether you want to cast the Discovered card or put it into your hand.
• Exiled cards are placed face up for all players to see.
• When you choose to cast a spell without paying its mana cost, you can't use its alternative costs.
• You can, however, pay additional costs such as Kicker. If your card has mandatory additional costs, such as one with Spree or a card like Village Rites, you must also pay those to cast it.
• If you Discover into a card with in its cost, such as Fireball or Braingeyser, then must be zero. Most times, you're better off choosing to put that card into your hand.
• If you can't cast the Discovered card, you'll put the card into your hand. At least that's a nice failsafe.
• Don't forget that the mana value of Split Cards is the sum of the costs of both halves. Assuming you can cast a Split Card with Discover, you may cast either half but not both halves.
• The most complex circumstance: Discovering into an Adventure, Split, or Modal Double-Faced card. In these cases, you might be able to cast the card with either set of characteristics depending on the Discover value. For example, if you Discover 3 into a Beanstalk Giant, you may cast Fertile Footsteps without paying its mana cost but not the seven-mana Creature. If you Discover 7, then you may cast either the Adventure spell or the Creature.

Top Five Discover Cards

Of the 28 cards printed to date with the Discover ability, a few cards stand out as most powerful.

1. Contest of Claws
2. Quintorius Kand
3. Pantlaza, Sun-Favored
4. Trumpeting Carnosaur
5. Chimil, the Inner Sun

5. Contest of Claws

Cheap spells with Discover are especially potent for their explosive potential. Contest of Claws is one of the cheapest ways to Discover, stapled to a respectable removal spell.

This card offers you a premium two-for-one, removing an opponent's Creature while also giving you another free spell assuming your Creature was bigger than your opponent's. While this may not be the flashiest Discover spell, its efficiency is what puts it into the top five.

4. Quintorius Kand

If you're looking for a Planeswalker that can Discover, Quintorius Kand is your answer. What's most impressive with Quintorius Kand is that its -3 ability still keeps it on the battlefield while also casting you a free spell via Discover and draining your opponent for two.

If you want to keep its Loyalty high, you could always use Quintorius's first ability and create a blocker. There's a good bit of versatility to this card, making it a powerful Planeswalker to consider in your Discover-themed decks.

3. Pantlaza, Sun-Favored

Dinosaur fans may rejoice with the printing of the Lost Caverns of Ixalan Commander (LCC) card, Pantlaza, Sun-Favored. Five mana gets you a 4/4 Creature that enters and Discovers X, where X is its power.

Then, as long as Pantlaza sticks around, its Discover X ability triggers once a turn whenever another Dinosaur enters the battlefield under your control. The Creature is a little bit of a lightning rod, but if left unchecked in the right Dinosaur Commander build, Pantlaza can help you accumulate value very rapidly.

2. Trumpeting Carnosaur

While Trumpeting Carnosaur's Discover ability is certainly powerful, the real attraction of this card is its versatility. It's essentially a split card -- for six mana you get a 7/6 Trampling Dinosaur that generates value by Discovering five. That's a powerful two-for-one.

However, if you're feeling pressured in the early game you can choose to pay three mana and Discard the Creature to deal three damage to a Creature or Planeswalker. Note that the second ability can't be stopped with a Counterspell since you're not actually casting a spell, making it a useful and difficult-to-stop removal spell should the need arise.

1. Chimil, the Inner Sun

If you like a bit of randomness to your Commander games and hate when your spells are countered, then I'd recommend including Chimil, the Inner Sun in your deck. Because it's a colorless Artifact, Chimil can fit into any Commander deck.

While six mana may be a steep cost, you quickly get a return on your investment. If your opponent can't destroy it before your end step, you immediately Discover 5. So, if your opponent destroys it afterwards, you at least get your Discovered card.

Then, with each subsequent turn, you Discover 5 over and over again at no additional cost. Chimil, the Inner Sun does its thing turn after turn, while also protecting all your spells from being countered. These two effects are potent if you can combine them, and Chimil's colorless nature makes this Legendary Artifact one of the most powerful Discover cards ever printed.

Wrapping It Up

Discover is a complex, yet powerful mechanic in MTG. Introduced just a few years ago, the ability has made waves in various formats including Standard and Commander. The ability is frequently compared to Cascade in that the two mechanics work very similarly.

The key differences include Discover's versatility with when it can trigger and the versatility of being able to place the Discovered card into your hand. These improvements offer Wizards of the Coast more design space.

As for the Power Level of Discover, it really boils down to the cards printed with the ability. Many players have nightmares facing down Bloodbraid Elf. Discover hasn't been broken in quite the same way as of yet.

That being said, Geological Appraiser is currently banned in Pioneer, so if WOTC isn't careful, Discover could develop the same reputation as Cascade.

In the meantime, Discover offers a fun, interesting way of generating value in a game of Magic. Hopefully, this ability will be utilized carefully so that it continues to be an interesting value machine for years to come.

Frequently Asked Questions for Discover

Even with detailed rules explanation, there are still many nuances associated with Discover.

Is Discover better than Cascade?

It depends.

For those unfamiliar with Cascade, the ability first appeared in Alara Reborn (ARB) back in 2009. It worked a little differently from Discover. When you cast a spell with Cascade, you trigger an ability where you Exile the top cards of your library until you find a nonland card that costs less than the card with Cascade.

Then you can play that card without paying its mana cost. You don't have the choice of putting it into your hand, so if you land on a spell you don't want to cast, such as a Fireball or a removal spell with no targets, your spell is stuck in Exile.

Additionally, Cascade was a Triggered Ability that happened when you cast spells, limiting the flexibility when creating cards with the keyword. You can trigger Discover in numerous ways: entering the battlefield, dying, activating with mana, end step, Planeswalker activations, and more. On the other hand, Cascade can only happen as a spell casting trigger.

So, in these ways, Discover is arguably a fixed version of Cascade. Is it more powerful, though? That depends on the cards that utilize the ability. Cascade has a history of problematically powerful cards, such as Bloodbraid Elf, and it'll take the printing of equally broken Discover cards for it to be considered by many to be "better than Cascade."

Can I counter Discover or Cascade spells?

If you attempt to counter a spell that triggers Discover or Cascade, you won't be happy with the outcome. The spell is countered, but the trigger still occurs, meaning your opponent will still get their free spell. You may be better off letting the trigger resolve and then countering the Discovered or Cascaded spell.

For example, when opponents used to Cascade into Hypergenesis in Legacy, you'd be better off holding your Counterspell for the Hypergenesis rather than the Violent Outburst that Cascaded into Hypergenesis.

Will we see Discover return to Standard?

It's possible. Interestingly, the Storm Scale doesn't currently include Discover. Cascade is on there as a seven, and Mark Rosewater shared that Discover is a "fixed" version of Cascade. With this evidence, it seems like the right set, especially a return to Ixalan, could bring us new cards with Discover.

Are there newer cards that have Discover?

Absolutely. While we haven't seen Discover in Standard since LCI, the ability has made a number of cameo appearances in supplemental products.

Examples include Monstrous Vortex from Modern Horizons 3 (MH3), Franklin Richards, Ascendant from Marvel Super Heroes Commander (MSC), and Ashaya's Enduring Bond from Mystery Booster Commander Edition (MBC).