Hive Mind — ruling 1

Hive Mind’s effect is mandatory. Each other player must copy the spell whether they want to or not.

Hive Mind — ruling 2

Hive Mind will copy any instant or sorcery spell, not just one with targets.

Hive Mind — ruling 3

If a player casts an instant or sorcery spell, Hive Mind’s ability triggers and is put on the stack on top of that spell. Hive Mind’s ability will resolve first. When it does, it creates a number of copies of that spell equal to the number of players in the game minus one. First the player whose turn it is (or, if that’s the player who cast the original spell, the player to that player’s left) puts their copy on the stack, choosing new targets for it if they like. Then each other player in turn order does the same. The last copy put on the stack will be the first one that resolves. (Note that the very last thing to happen is that the original spell resolves.)

Hive Mind — ruling 4

The copies that Hive Mind’s ability creates are created on the stack, so they’re not “cast.” Abilities that trigger when a player casts a spell (like Hive Mind’s ability itself) won’t trigger.

Hive Mind — ruling 5

Each copy will have the same targets as the spell it’s copying unless its controller chooses new ones. That player may change any number of the targets, including all of them or none of them. If, for one of the targets, the player can’t choose a new legal target, then it remains unchanged (even if the current target is illegal).

Hive Mind — ruling 6

If the spell that’s copied is modal (that is, it says “Choose one —” or the like), the copy will have the same mode. A player can’t choose a different one.

Hive Mind — ruling 7

If the spell that’s copied has an X whose value was determined as it was cast (like Earthquake does), the copy has the same value of X.

Hive Mind — ruling 8

A copy’s controller can’t choose to pay any additional costs for the copy. However, effects based on any additional costs that were paid for the original spell are copied as though those same costs were paid for the copy too.

Hive Mind : règles, fonctionnement et interactions (MTG)

Hive Mind is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Whenever a player casts an instant or sorcery spell, each other player copies that spell. Each of those players may choose new targets for their copy.

How it works : Hive Mind

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
Hive Mind’s effect is mandatory. Each other player must copy the spell whether they want to or not.
No other card is named in this ruling.
#2October 1, 2009· Wizards of the Coast
Hive Mind will copy any instant or sorcery spell, not just one with targets.
No other card is named in this ruling.
#3October 1, 2009· Wizards of the Coast
If a player casts an instant or sorcery spell, Hive Mind’s ability triggers and is put on the stack on top of that spell. Hive Mind’s ability will resolve first. When it does, it creates a number of copies of that spell equal to the number of players in the game minus one. First the player whose turn it is (or, if that’s the player who cast the original spell, the player to that player’s left) puts their copy on the stack, choosing new targets for it if they like. Then each other player in turn order does the same. The last copy put on the stack will be the first one that resolves. (Note that the very last thing to happen is that the original spell resolves.)
No other card is named in this ruling.
#4October 1, 2009· Wizards of the Coast
The copies that Hive Mind’s ability creates are created on the stack, so they’re not “cast.” Abilities that trigger when a player casts a spell (like Hive Mind’s ability itself) won’t trigger.
No other card is named in this ruling.
#5October 1, 2009· Wizards of the Coast
Each copy will have the same targets as the spell it’s copying unless its controller chooses new ones. That player may change any number of the targets, including all of them or none of them. If, for one of the targets, the player can’t choose a new legal target, then it remains unchanged (even if the current target is illegal).
No other card is named in this ruling.
#6October 1, 2009· Wizards of the Coast
If the spell that’s copied is modal (that is, it says “Choose one —” or the like), the copy will have the same mode. A player can’t choose a different one.
No other card is named in this ruling.
#7October 1, 2009· Wizards of the Coast
If the spell that’s copied has an X whose value was determined as it was cast (like Earthquake does), the copy has the same value of X.
No other card is named in this ruling.
#8October 1, 2009· Wizards of the Coast
A copy’s controller can’t choose to pay any additional costs for the copy. However, effects based on any additional costs that were paid for the original spell are copied as though those same costs were paid for the copy too.
No other card is named in this ruling.
#9October 1, 2009· Wizards of the Coast
If a copy says that it affects “you,” it affects the controller of the copy, not the controller of the original spell. Similarly, if a copy says that it affects an “opponent,” it affects an opponent of the copy’s controller, not an opponent of the original spell’s controller.
No other card is named in this ruling.

Popular combos

Real combos played by the community, sorted by popularity.

#1
Hive Mind + Enter the Infinite + Howling Mine
Each opponent loses the gameInfinite card drawInfinite card draw for each opponentInfinite draw triggers
1Cast Enter the Infinite by paying .
2Hive Mind triggers, causing each opponent to create a copy of Enter the Infinite.
3Resolve each Enter the Infinite, causing each player to draw their entire library, put a card from their hand on top of their library, and have no maximum hand size until their next turn.
4At the beginning of each opponent's draw step, Howling Mine triggers, causing them to draw an additional card and lose the game due to drawing from an empty library.

#1
Hive Mind + Enter the Infinite + Howling Mine
Each opponent loses the gameInfinite card drawInfinite card draw for each opponentInfinite draw triggers
1Cast Enter the Infinite by paying .
2Hive Mind triggers, causing each opponent to create a copy of Enter the Infinite.
3Resolve each Enter the Infinite, causing each player to draw their entire library, put a card from their hand on top of their library, and have no maximum hand size until their next turn.
4At the beginning of each opponent's draw step, Howling Mine triggers, causing them to draw an additional card and lose the game due to drawing from an empty library.

#4
Opposition Agent + Hive Mind + Doomsday
Exile each opponent's libraryNear-infinite lifeloss
1Cast Doomsday by paying .
2Hive Mind triggers, causing each opponent to copy Doomsday.
3Resolve the first opponent's Doomsday, searching their library and/or graveyard for any five cards, exiling them due to Opposition Agent, exiling the rest of their library and graveyard, and causing them to lose half their life, rounded up.
4Repeat step 3 for each other opponent.

#5
Hive Mind + Doomsday + Ashiok, Dream Render
Exile each opponent's libraryNear-infinite lifeloss
1Activate Ashiok by removing a loyalty counter from it, causing target player to mill four cards and exiling each opponent's graveyard.
2Cast Doomsday by paying .
3Hive Mind triggers, causing each opponent to copy Doomsday.
4Resolve an opponent's Doomsday, causing them to exile their library and not search for any cards due to Ashiok, and lose half their life total, rounded up.
5Repeat step 4 for each remaining opponent.
6Resolve your Doomsday, searching your library and/or graveyard for five cards, exiling the rest of your library and graveyard, and putting the five chosen cards on top of your library in any order, and losing half your life total, rounded up.

#8
Disciple of Caelus Nin + Hive Mind + Teferi's Protection
Permanently phase out all permanents opponents controlMass Land Denial
1On the end step prior to your turn, cast Teferi's Protection by paying .
2Hive Mind triggers, causing each opponent to copy Teferi's Protection.
3Resolve all Teferi's Protections, causing all players to phase out all permanents they control.
4During your next untap step, Disciple of Caelus Nin and all other phased out permanents you control phase in.
5Disciple of Caelus Nin prevents all permanents your opponents own that are phased out from phasing in, causing them to stay phased out indefinitely.

Interactions with other cards

These cards' text mentions Hive Mind.

Zellix, Sanity Flayer

Hive Mind — Whenever a player mills one or more creature cards, you create a 1/1 black Horror creature token. {1}, {T}: Target player mills three cards. Choose a Background (You can have a Background as a second commander.)