How Mana Abilities Break Magic: The Gathering

Abhi Vaidyanatha
13 min readApr 1, 2024
A picture of the mana confluence card with the secret lair mana confluence in the background. Text says: Mana abilities are weird.

Mana abilities usually require players to understand one thing: “I tap lands, rocks, and dorks to play spells.” But when they ask more of your brain, it gets real weird. Here’s some unnecessarily thought-provoking questions:

  1. You control a Myr Retriever. You sacrifice it to Krark-Clan Ironworks while paying for a spell. When does this Triggered Ability resolve?
  2. Can you activate mana abilities while casting a spell with 0 mana cost? (e.g. Mox Opal) Also, why would you want to?
  3. You control four untapped Forests and Selvala, Explorer Returned. Selvala taps to make each player reveal and draw the top card of their library, adding a green mana for each nonland revealed. Can you attempt to cast a Colossal Dreadmaw, which you theoretically can pay for if the right cards are revealed? What happens if you activate the ability, both players draw a card, and then you can’t pay for it? Why didn’t you just activate Selvala before casting the Colossal Dreadmaw?

Take a deep breath, and let’s get started. Here’s the basic stuff from the Comprehensive Rules to get us on the right path on determining what is and what isn’t a mana ability:

605.1a An activated ability is a mana ability if it meets all of the following criteria: it doesn’t require a target (see rule 115.6), it could add mana to a player’s mana pool when it resolves, and it’s not a loyalty ability.

Furthermore, here’s something you may already know about them:

An activated mana ability doesn’t go on the stack, so it can’t be targeted, countered, or otherwise responded to. Rather, it resolves immediately after it is activated.

Finally, here’s the exact steps for casting a spell or resolving an ability in Magic, which players often perform out of order:

  1. Move the spell or ability to the stack.
  2. Announce choices, modes, additional costs, alternative costs if relevant.
  3. Announce targets.
  4. Distribute damage or effects.
  5. Check legality (rewind the game to before Step 1 if not).
  6. Determine total costs.
  7. Pay the costs.

Generally, it is common to see someone tap their lands to add mana to their mana pool before casting a spell. This is valid, but it’s also valid to wait to pay for the spell until the final step of casting a spell:

605.3a A player may activate an activated mana ability whenever they have priority, whenever they are casting a spell or activating an ability that requires a mana payment, or whenever a rule or effect asks for a mana payment, even if it’s in the middle of casting or resolving a spell or activating or resolving an ability.

When you activate a mana ability this way, you are now using an activated ability in the middle of casting a spell! This has weird consequences. Taking all of this information in context, let’s check out the scenarios we described at the start.

Triggered Abilities from Mana Abilities

A picture of the card, krark-clan ironworks from magic the gathering
There was a real affinity for this card.

Krark-Clan Ironworks (commonly abbreviated as KCI) was banned in the Modern format 5 years ago. The card required a higher understanding of the comprehensive rules than should be required to play the game, making it difficult to explain during commentary of professional matches and difficult to explain to new players. It caused delays in tournaments and enabled a powerful archetype that was reaching Top 8 at big events consistently, even though it was part of a lesser-seen deck. We’re going to learn about why it was banned today!

KCI, notably, meets all the requirements for a mana ability, and therefore can be activated while paying costs for a spell. Subsequently, it may not surprise you when I mention that a bread and butter combo for KCI decks during this period involved executing a combo in the middle of casting a spell. I’m going to explain the combo here, but if you would like a supplementary explanation, both this video from JudgingFtW and this blog from Ask a Magic Judge will give you a full understanding of the combo.

The three cards that represent the KCI combo side by side: Krark-Clan Ironworks, Myr Retriever, and Scrap Trawler.
An artifact of its time.

To start, Myr Retriever and Scrap Trawler both have on death effects that return an artifact to hand from the graveyard. Scrap Trawler returns an artifact of lesser mana value from the graveyard when it dies or another artifact dies. Myr Retriever returns any artifact from the graveyard when it dies. Our combo wants to accomplish the following:

  • Sacrifice Myr Retriever to KCI
  • Sacrifice Scrap Trawler to KCI
  • Trigger Myr Retriever on its death, returning Scrap Trawler.
  • Trigger Scrap Trawler on Myr Retriever’s death, returning a 0 or 1 cost artifact.
  • Trigger Scrap Trawler on its death, returning Myr Retriever.

These five statements describe a normally impossible game state to achieve. Let’s try to do this combo without implementing any special tactics and see why it doesn’t work.

Scenario 1

  1. You sacrifice Myr Retriever to KCI. Its trigger goes on the stack. You must select targets when an ability goes on the stack, so it cannot see Scrap Trawler in the graveyard. Scrap Trawler triggers for Myr Retriever dying as well, letting you return a 0 or 1 cost artifact.
  2. You sacrifice Scrap Trawler to KCI. Its trigger goes on the stack immediately, letting you target Myr Retriever.
  3. Results: An arbitrary artifact is returned to hand from Myr Retriever’s trigger. An artifact of mana value 0 or 1 is returned to hand from Scrap Trawler’s first trigger. Myr Retriever is returned to hand from Scrap Trawler’s second trigger. Scrap Trawler remains in the graveyard.

Scenario 2

  1. You sacrifice Scrap Trawler to KCI. Its trigger goes on the stack immediately, forcing you to select targets now, so it cannot see Myr Retriever in the graveyard.
  2. You sacrifice Myr Retriever to KCI. Its trigger goes on the stack immediately, letting you target Scrap Trawler.
  3. Results: An arbitrary artifact of mana value 2 or less is returned to hand from Scrap trawler’s trigger. Scrap Trawler is returned to hand from Myr Retriever’s trigger. Myr Retriever remains in the graveyard.

If we look closely here, we can find the root cause: both Triggered Abilities make you select targets immediately when the mana ability is activated because they go on the stack immediately. So if we want to ever want this combo to work, we need to have both Triggered Abilities go on the stack at the same time. Weirdly, this is possible. Remember when I said that we can activate mana abilities while casting a spell? Let’s see what happens when we try to do that.

So, for example, let’s say that you sacrifice your Myr Retriever and Scrap Trawler to Krark-Clan Ironworks while paying for a Sol Ring. So what happens to the Retriever and Trawler triggers? Do you resolve them immediately? If you have two triggers, which one happens first?

I mentioned JudgingFtW earlier, and he invented my favorite analogy for how the game handles triggered abilities: As you meet the conditions for a trigger, Rules Faeries arrive and start writing down the triggers on a whiteboard. Right before players receive priority, the Faeries put all the triggers they wrote down on the stack. This may feel intuitive for triggers that happen when you cast a spell, as those go on the stack in response to a successful cast, but this analogy provides a useful framework to explain how abilities resolve when triggered in the middle of casting a spell.

Let’s try and now resolve the situation above to successfully pull off the KCI combo with our Faerie friends.

  1. You put the Sol Ring on the stack and go to pay for costs.
  2. You first sacrifice Myr Retriever to KCI to pay for the Sol Ring and trigger Myr Retriever’s ability. The Faeries write this down.
  3. Scrap Trawler sees Myr Retriever die and triggers its own ability. The Faeries write this down.
  4. You sacrifice Scrap Trawler to KCI and triggers its own ability. The Faeries write this down.
  5. Sol Ring is officially cast after paying costs.
  6. The Faeries see that a player is about to get priority and put the three triggers on the stack, politely asking you what order you want them in.
  7. Scrap Trawler, Myr Retriever, and another artifact of mana value 0 or 1 can all be targeted and returned to hand. You have three colorless mana in your mana pool left from your KCI activations.

This all works because Myr Retriever and Scrap Trawler were now both in the graveyard at the same time, because the triggers had to wait to go on the stack. Therefore, they could target each other with their triggers, returning both of them to hand since we sacrificed them while casting a spell! Wild stuff.

Zero Cost Spells

Image of the secret lair violent outburst magic the gathering card, which includes some very cute cats playing together.
I’ll use any excuse to display this card.

Some spells in the game cost 0 mana to play. They might be like Mox Opal and have a 0 in the top right for their mana, or they might be the result of another card that lets you play something for free (e.g. Cascade).

With our exploration of Krark-Clan Ironworks above, we now know that there may be an incentive to use mana abilities while casting a spell, even if the spell has a mana cost of 0! But, is it legal to do this?

Flatly, the answer is no. We can derive it from this section of the CR:

601.2g If the total cost includes a mana payment, the player then has a chance to activate mana abilities (see rule 605, “Mana Abilities”). Mana abilities must be activated before costs are paid.

Note that this states “if the total cost includes a mana payment.” While 0 is a mana cost, it does not incur a payment, so you cannot activate mana abilities while casting a 0 mana spell. This naturally also applies for any spell that is cast with an effect that states “You may cast that card without paying its mana cost.” So you can’t sacrifice any artifacts to Krark-Clan Ironworks while casting a 0 mana-cost spell.

Mana Abilities with Variable Results

A picture of the card, axebane guardian from magic the gathering.
Arcades’ biggest enabler.

There are some mana abilities that produce variable mana, where that value can change based on the board state. One such example is Arcades the Strategist’s favorite mana dork, Axebane Guardian, who adds any color mana based on the amount of creatures you control with Defender. Because of the variable nature, there are some cases where you’ve started casting a spell intending to pay the costs, but you make a gameplay error that prevents you from doing so.

Ashnod squeezing water from walls.

Consider the following scenario:

Anya and Nellie are playing at a competitive event. Anya has an Ashnod’s Altar in play with their Axebane Guardian. All their lands are tapped and they have no mana in their mana pool. They have 4 creatures with Defender in play, including Axebane Guardian. Anya goes to pay for a Colossal Dreadmaw, and uses Ashnod’s Altar to sacrifice one of their Defenders, Wall of Omens, to add 2 colorless mana before activating Axebane Guardian. Anya goes to tap Axebane Guardian and realizes that they can only add 3 green mana to the mana pool since they sacrificed a Defender. Since this cast is now illegal, Nellie calls a judge. There’s only one judge, who just went off to her well-deserved lunch break during the end of Round 8. Can the players resolve this themselves?

Thankfully, the game has the following rule built in:

730.1. If a player takes an illegal action or starts to take an action but can’t legally complete it, the entire action is reversed and any payments already made are canceled. No abilities trigger and no effects apply as a result of an undone action. If the action was casting a spell, the spell returns to the zone it came from. Each player may also reverse any legal mana abilities that player activated while making the illegal play, unless mana from those abilities or from any triggered mana abilities they caused to trigger was spent on another mana ability that wasn’t reversed. Players may not reverse actions that moved cards to a library, moved cards from a library to any zone other than the stack, caused a library to be shuffled, or caused cards from a library to be revealed.

So in this case, the players are legally allowed to move the Wall of Omens from the graveyard to the battlefield and backup to the point before the spell was cast, and try again, sacrificing the creatures in a different order now.

The cool part about this example is that it displays a situation that shows a definitive benefit to casting a spell by the book by paying for costs during the casting process! Note that if Anya decided to sacrifice the Wall of Omens before casting the spell, they would not be allowed to reverse this automatically, and would instead have to ask a judge to reverse this, as I covered in my article on reversing decisions.

Mana Abilities with Non-Deterministic Results

A picture of the card, Selvala Returned from magic the gathering.
Why is this a mana ability?

Now, using this knowledge that the game lets us backup if we try to cast an illegal spell, let’s answer the question I posed at the beginning of the article:

You control four untapped Forests and Selvala, Explorer Returned. Can you attempt to cast a Colossal Dreadmaw, which you theoretically can pay for if you reveal the right cards with Selvala? What happens if you go to pay costs, activate the ability, each player draws, and then you can’t pay for it?

I’ll cut to the chase on the first question. No, you cannot attempt to intentionally pay for the Colossal Dreadmaw with 4 Forests and a Selvala during the spellcasting process. This squarely fits the requirements for Cheating under the Infraction Procedure Guide, which will lead to immediate disqualification. This is because you intentionally tried to commit an illegal action for benefit, even if there was a chance it wasn’t illegal. This sounds harsh, but it is practically impossible to get into this scenario without manufacturing it.

However, you are totally allowed to do the natural play and activate Selvala before going to cast Colossal Dreadmaw, checking to see if you can generate the necessary mana. This may sound obvious to most players because this is the natural way Magic is played. However, we covered that there are some hyper-technical gameplay benefits for waiting to pay costs until you’re in the spellcasting process.

Now for the fun part. What if you tried to surprise your friends at casual Commander night with this cool interaction to show how much you know about esoteric rules?

Since this is casual Commander, no judge is going to stop us from making an illegal cast, so we can just go for it. As we’ve said before, Selvala’s ability is indeed a mana ability. As we’ve learned, this means that we can activate it in the middle of casting our Colossal Dreadmaw. This means that we can go to pay for it, tap our 4 Forests, and if two players reveal a nonland card, you can successfully cast the Dreadmaw! No harm, no foul.

But if not enough people reveal a nonland card, you just made every player draw a card while illegally casting a spell. Thankfully, the game did actually consider this edge case, which we read earlier:

Each player may also reverse any legal mana abilities that player activated while making the illegal play, unless mana from those abilities or from any triggered mana abilities they caused to trigger was spent on another mana ability that wasn’t reversed. Players may not reverse actions that moved cards to a library, moved cards from a library to any zone other than the stack, caused a library to be shuffled, or caused cards from a library to be revealed.

So you return to before you cast Colossal Dreadmaw, untap your Forests, and don’t untap Selvala, since it moved cards from libraries to a zone that wasn’t the stack.

Learning From the Past

Original on the left. Errata on the right.

Funny enough, this whole rules debacle could be solved easily by issuing an errata to Selvala, writing at the end of her ability: “Activate this ability only any time you could cast an instant.” This prevents the ability from being activated during the spellcasting process, as you can’t cast instants during the process of casting another spell.

Lion’s Eye Diamond caused similar issues before, and was issued a functional errata as displayed above. Players would activate Lion’s Eye Diamond while paying for a spell, discarding their hand, and then would pick up their entire hand from the graveyard if the cast was illegal.

Considering that Lion’s Eye Diamond sees active play in Legacy and cEDH, I can see why they prioritized this. Selvala sees no play in constructed formats, but since they just reprinted her in a Murders at Karlov Manor Commander PreCon, I’m disappointed that they didn’t take the opportunity to do this errata. After this, you will start seeing these weird cases in the wild and cards like Millikin will begin to stand out to you as gameplay issues waiting to happen.

Conclusion

Phew, that was a lot. Here’s what we learned today:

  1. You can pay for a spell by adding mana to your mana pool before casting it, or during the “pay costs” step of casting the spell.
  2. Triggered abilities that trigger while paying mana costs during casting a spell wait to go on the stack until the spell is cast. Then they all go onto the stack at the same time.
  3. You can’t activate mana abilities while casting a spell with mana cost 0 to “over pay.” The “pay costs” step is skipped entirely when the spell is free.
  4. If you start casting a spell, then go to activate mana abilities to pay costs during the cast, and you accidentally make it so that you can’t pay for the spell, the game rewinds, you untap everything except your mana abilities that interacted with libraries, and you get another try at it.
  5. If you start casting a spell, then go to activate mana abilities to pay costs during the cast, and you intentionally make it so that you can’t pay for the spell, you get disqualified.
  6. Mana abilities that interact with libraries, hands, or other impactful game zones should be printed at Instant speed.

Thanks for reading!

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