Rules Primer- Priority and the Stack

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KrazyCaley

12 February 2010

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Per requests send to my tappedout e-mail ([email protected]), an explanation of how priority and the stack works-

"Priority" at its heart means "who has the right to take actions like activating abilities and casting spells right now?"

You may not, I repeat, NOT cast spells at any time. You must have priority in order to activate abilities and cast spells. What gives a player priority? Priority tip #1- In most situations, the player whose turn it is (the "active player") gets priority first in situations where players can ordinarily take actions. An ordinary game of Magic does not usually proceed mechanically through each of the many steps/phases of a turn, and things like priority are integrated fairly well without explicit reference. Note that some steps, like for instance the untap and cleanup steps, never give players priority.

However, in most steps, the general structure is this- whatever is supposed to happen during that step happens first (i.e., in the draw step, the active player draws a card, in the upkeep step, effects that trigger "at the beginning of your upkeep" trigger and go onto the stack, but more on that later). Then, the active player gets priority to cast spells and activate abilities.

This brings us to another important priority point- The player who has priority keeps it until he/she relinquishes it. That player may cast as many spells and activate as many abilities as he/she wants until passing priority

Case in point- Suppose I have two cards in hand, and my opponent has one, and we both know what each other's hands contain- his is a Counterspell. Mine is Progenitus, plus a fictional card whose rules text reads as follows- "Split Second. Players may not cast spells until end of turn." (If you don't remember how split second works, essentially it means that once you cast a split second spell, players can't take any further actions that use the stack until the split second spell resolves. It's a little like interrupts from back in the day, if anyone remembers that. See the reminder text on Sudden Death.) My main phase has just begun, and since it's my turn, I have priority first.

Many players might think that if player #1 casts Progenitus and puts it onto the stack, then player #2 automatically gets priority to use that Counterspell before player #1 can do anything else. This is not so. Priority means you get to keep casting and activating until you are satisfied. So in this case, player #1 gets to cast Progenitus, still keeps priority, and then puts their split second "no one can cast spells" spell onto the stack. Since it has split second, that spell resolves before anything else can happen, and player #2 is stuck with a Counterspell in their hand; Progenitus will resolve.

Now let's examine the stack.

"The stack" is an abstract space where spells and abilities go when they are cast/used. Let's start with the very basics. Stack tip #1- If there is anything on the stack, then both players must pass priority before anything on the stack resolves

Basic example- I cast Lightning Bolt during my main phase. Lightning Bolt, before it does its 3 damage, goes onto the stack. I still have priority. However, I have nothing else to cast, so I pass priority to my opponent. My opponent has no responses to lightning bolt, so they also pass priority (note that this rarely actually verbally occurs during a game, but nevertheless, it happens implicitly). Since both players have passed priority, the latest thing to go on the stack, namely lightning bolt, resolves and does its 3 damage. I now have priority again, because Stack tip #2- Once the stack is clear, the active player immediately receives priority.

Example- I cast Jace Beleren. He goes on the stack. I have nothing else to cast, so I pass priority. My opponent has no responses and passes priority. Jace resolves. Since I am the active player, I IMMEDIATELY receive priority, and can put one of Jace's abilities on the stack before my opponent can do anything.

Stack tip #3- Last in, first out. When both players pass priority without doing anything and there is something on the stack, the LAST THING that was put on the stack resolves.

Suppose I have a Mother of Runes out, untapped and not suffering from summoning sickness. It is my opponent's turn. He has priority and casts Lightning Bolt targeting Mother of Runes. Lightning Bolt goes on the stack. My opponent has nothing else to do, so he passes priority. Now I have priority. I use it to activate Mother of Runes' ability, tapping her, targeting herself and choosing red. Stack tip #4- All spells, triggered abilities, and activated abilities use the stack. Because Mother of Runes' ability is an activated ability, it goes on the stack. I pass priority. (Note that even though both players have passed priority at this point, nothing resolves because we've been doing stuff. You have to pass priority without doing anything for the turn to move forward). My opponent passes priority, having nothing else to do. So do I. Now the last thing on the stack resolves- the activated ability of Mother of Runes targeting herself. She gains protection from red. She does not tap, because she already tapped when I activated the ability. (Paying the cost of an ability happens immediately, without using the stack, and can't be responded to).

Stack tip #5- EVERY time a spell or effect comes off the stack, the active player receives priority again and the cycle begins anew. Lightning Bolt is still on the stack at the point. Only Mother of Runes' activated ability came off, since it was the most recent thing to go on. My opponent receives priority with lightning bolt pending. He uses it to cast Thoughtlace targeting Lightning Bolt. He has nothing else to do and passes priority. I have no responses and I pass priority. Once priority is dealt with, Thoughtlace resolves and Lightning Bolt becomes a blue spell, still on the stack. My opponent receives priority again. So do I, even though I wish I had a Red Elemental Blast at this point. Alas I do not. So, finally, the tortured Lightning Bolt resolves. It deals three damage to Mother of Runes, whose pro-red does nothing to save her from the newly-blue bolt.

Here's a quiz for you. I control Dralnu, Lich Lord and Royal Assassin, and no other permanents. My opponent controls Prodigal Sorcerer and a bunch of islands. My opponent, during his main phases, activates Prodigal Sorcerer targeting Dralnu, Lich Lord, then passes priority. I activate Royal Assassin targeting Prodigal Sorcerer, then pass priority. My opponent casts the only spell in his hand, Twitch, targeting Prodigal Sorcerer with the untap effect, then passes priority. I have nothing left to do, and I pass priority. Twitch resolves. Then my opponent uses Prodigal Sorcerer's ability again, targeting Royal Assassin. Then he passes priority, and so do I. Indeed, neither of us have anything left to do and we continuously pass priority until the stack is clear.

Three questions:

1- Identify, in the order they were put there, all the things that were on the stack right after Prodigal Sorcerer's ability was used for the second time.

2- Tell me the chronology of what happens as all those effects that were put on the stack resolve, and what the end result is.

3- Tell me the gameplay error made by my opponent.

Answers follow after a break

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- 1- The stack looks like this after the second activation of Prodigal Sorcerer-

I- Prodigal Sorcerer's first activation- "Prodigal Sorcerer does 1 damage to Dralnu, Lich Lord."

II- Royal Assassin's first activation- "Royal Assassin destroys target tapped Prodigal Sorcerer."

III- Prodigal Sorcerer's second activation- "Prodigal Sorcerer does 1 damage to Royal Assassin."

Twitch is no longer on the stack because it resolved.

2- First, Prodigal Sorcerer's second activation occurs. It does 1 damage to Royal Assassin, and Royal Assassin is destroyed. (A creature dying due to damage is not an ability, it is a state-based effect. Perhaps more on that in a later article). Then, Royal Assassin's ability resolves and destroys the tapped Prodigal Sorcerer. (Just because a creature has been destroyed does NOT mean that those abilities of that creature that were put on the stack before/as it died can't resolve). Then, Prodigal Sorcerer's first activation resolves and tries to deal 1 damage to Dralnu, Lich Lord. However, a replacement effect stops the damage from happening and instead I have to sacrifice a permanent when the ability resolves. Since Dralnu is the only permanent I have, I sacrifice him. End result- all the creatures are dead and only my opponent's islands remain.

3- My opponent activated Prodigal Sorcerer for the second time too early. After casting Twitch and seeing it resolve, the next thing on the stack was Royal Assassin's ability, which only works if the creature it targets is still tapped when the ability resolves. Since Twitch untapped the Prodigal Sorcerer, my opponent should have waited for Royal Assassin's ability to resolve before activating Prodigal Sorcerer again. If he had done so, Royal Assassin's ability would have resolved and been countered since the Sorcerer was no longer tapped. THEN my opponent could have activated Prodigal Sorcerer again targeting Royal Assassin, and he would have had the same result, only he gets to keep his Prodigal Sorcerer.

And that was a SIMPLE example. The stack and priority can get confusing and complicated at times, but hopefully that will help those of you who have been asking with the basics. If you have questions, I'm happy to answer them below.