Alrund, God of the Cosmos

Alrund, God of the Cosmos, ruler of all that is, was accidentally printed without the words "revealed this way." Taken literally, you would put all cards of the chosen type into your hand. Like, all of them. From anywhere in the cosmos. We tidied this up prior to release.

Alrund, God of the Cosmos was:

Alrund gets +1/+1 for each card in your hand and each foretold card you own in exile.
At the beginning of your end step, choose a card type, then reveal the top two cards of your library. Put all cards of the chosen type into your hand and the rest on the bottom of your library in any order.

New text:

Alrund gets +1/+1 for each card in your hand and each foretold card you own in exile.
At the beginning of your end step, choose a card type, then reveal the top two cards of your library. Put all cards of the chosen type revealed this way into your hand and the rest on the bottom of your library in any order.

Chains of Mephistopheles

Chains of Mephistopheles was templated in a way that assumed each turn would have but a single draw step. Now, in the time of Sphinx of the Second Sun, that is a foolish assumption.

Chains of Mephistopheles was:

If a player would draw a card except the first one they draw in their draw step each turn, that player discards a card instead. If the player discards a card this way, they draw a card. If the player doesn't discard a card this way, they mill a card.

New text:

If a player would draw a card except the first one they draw in each of their draw steps, that player discards a card instead. If the player discards a card this way, they draw a card. If the player doesn't discard a card this way, they mill a card.

Drana, the Last Bloodchief

Drana's template was missing "an additional," so we added it. That text is there to help clarify what happens if the creature entering the battlefield has its own way of entering with +1/+1 counters on it.

Drana, the Last Bloodchief was:

Flying
Whenever Drana, the Last Bloodchief attacks, defending player chooses a nonlegendary creature card in your graveyard. You return that card to the battlefield with a +1/+1 counter on it. The creature is a Vampire in addition to its other types.

New text:

Flying
Whenever Drana, the Last Bloodchief attacks, defending player chooses a nonlegendary creature card in your graveyard. You return that card to the battlefield with an additional +1/+1 counter on it. The creature is a Vampire in addition to its other types.

Grim Reminder

This card got skipped in the recent "card" to "spell" updates, a Grim Reminder of the importance of precision.

Grim Reminder was:

Search your library for a nonland card and reveal it. Each opponent who cast a card this turn with the same name as that card loses 6 life. Then shuffle your library.
{B}{B}: Return Grim Reminder from your graveyard to your hand. Activate this ability only during your upkeep.

New text:

Search your library for a nonland card and reveal it. Each opponent who cast a spell this turn with the same name as that card loses 6 life. Then shuffle your library.
{oBoB}: Return Grim Reminder from your graveyard to your hand. Activate this ability only during your upkeep.

Idol of Endurance

Some simple editorial cleanup here, as we removed an errant "the" from this card's template.

Idol of Endurance was:

When Idol of Endurance enters the battlefield, exile all creature cards with converted mana cost 3 or less from your graveyard until Idol of Endurance leaves the battlefield.
{1}{W}, {T}: Until end of turn, you may cast a creature spell from among the cards exiled with Idol of Endurance without paying its mana cost.

New text:

When Idol of Endurance enters the battlefield, exile all creature cards with converted mana cost 3 or less from your graveyard until Idol of Endurance leaves the battlefield.
{1}{W}, {T}: Until end of turn, you may cast a creature spell from among cards exiled with Idol of Endurance without paying its mana cost.

Jeska, Thrice Reborn

We inadvertently used "it" in rules text when we should have used "her."

Jeska, Thrice Reborn was:

Jeska, Thrice Reborn enters the battlefield with a loyalty counter on it for each time you've cast a commander from the command zone this game.
0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.
−X: Jeska, Thrice Reborn deals X damage to each of up to three targets.
Jeska, Thrice Reborn can be your commander.
Partner

New text:

Jeska, Thrice Reborn enters the battlefield with a loyalty counter on her for each time you've cast a commander from the command zone this game.
0: Choose target creature. Until your next turn, if that creature would deal combat damage to one of your opponents, it deals triple that damage to that player instead.
−X: Jeska, Thrice Reborn deals X damage to each of up to three targets.
Jeska, Thrice Reborn can be your commander.
Partner

Quicken and Savage Summoning

Two cases that, in retrospect, should have used "spell" rather than "card." Both cards refer to the next spell you cast of a particular type.

Quicken was:

The next sorcery card you cast this turn can be cast as though it had flash. (It can be cast any time you could cast an instant.)
Draw a card.

New text:

The next sorcery spell you cast this turn can be cast as though it had flash. (It can be cast any time you could cast an instant.)
Draw a card.

Savage Summoning was:

This spell can't be countered.
The next creature card you cast this turn can be cast as though it had flash. That spell can't be countered. That creature enters the battlefield with an additional +1/+1 counter on it.

New text:

This spell can't be countered.
The next creature spell you cast this turn can be cast as though it had flash. That spell can't be countered. That creature enters the battlefield with an additional +1/+1 counter on it.

Skinshifter

We've improved the templating of modal abilities over the years. A more recent innovation was the realization that we could just include activation instructions of a modal activated ability up front, before the modes themselves. Skinshifter certainly would appreciate this, and now it can.

Skinshifter was:

{G}: Choose one —

  • Until end of turn, Skinshifter becomes a Rhino with base power and toughness 4/4 and gains trample. Activate this ability only once each turn.
  • Until end of turn, Skinshifter becomes a Bird with base power and toughness 2/2 and gains flying. Activate this ability only once each turn.
  • Until end of turn, Skinshifter becomes a Plant with base power and toughness 0/8. Activate this ability only once each turn.

New text:

{oG}: Choose one. Activate this ability only once each turn.

  • Until end of turn, Skinshifter becomes a Rhino with base power and toughness 4/4 and gains trample.
  • Until end of turn, Skinshifter becomes a Bird with base power and toughness 2/2 and gains flying.
  • Until end of turn, Skinshifter becomes a Plant with base power and toughness 0/8.

Introduction
Comprehensive Rules Changes
Oracle Changes