Kefnet's Last Word — ruling 1

The control-change effect of Kefnet’s Last Word lasts indefinitely. It doesn’t wear off during the cleanup step.

Kefnet's Last Word — ruling 2

If the target permanent is an illegal target by the time Kefnet’s Last Word resolves, the entire spell doesn’t resolve. Your lands will untap during your next untap step as normal.

Kefnet's Last Word — ruling 3

Gaining control of a creature doesn’t cause you to gain control of any Auras or Equipment attached to it. They’ll remain attached, but an Aura’s effect that affects “you” still affects its controller rather than you, the controller of an Equipment can move it during their next main phase, and so on.

Kefnet's Last Word — ruling 4

In a multiplayer game, if a player leaves the game, all cards that player owns leave as well, and any effects that give the player control of permanents immediately end.

Kefnet's Last Word — ruling 5

No lands that you control will untap during your next untap step, even lands that aren’t tapped as this spell resolves. This includes lands that enter the battlefield after this spell resolves.

Kefnet's Last Word — ruling 6

If more than one spell says that lands you control don’t untap during your next untap step, the effects will all wear off during that untap step. You’ll untap lands you control during your untap step after that one.

Kefnet's Last Word : règles, fonctionnement et interactions (MTG)

Kefnet's Last Word 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

Gain control of target artifact, creature, or enchantment. Lands you control don't untap during your next untap step.

How it works : Kefnet's Last Word

Original English text — Wizards of the Coast / Scryfall

#1July 14, 2017· Wizards of the Coast
The control-change effect of Kefnet’s Last Word lasts indefinitely. It doesn’t wear off during the cleanup step.
No other card is named in this ruling.
#2July 14, 2017· Wizards of the Coast
If the target permanent is an illegal target by the time Kefnet’s Last Word resolves, the entire spell doesn’t resolve. Your lands will untap during your next untap step as normal.
No other card is named in this ruling.
#3July 14, 2017· Wizards of the Coast
Gaining control of a creature doesn’t cause you to gain control of any Auras or Equipment attached to it. They’ll remain attached, but an Aura’s effect that affects “you” still affects its controller rather than you, the controller of an Equipment can move it during their next main phase, and so on.
No other card is named in this ruling.
#4July 14, 2017· Wizards of the Coast
In a multiplayer game, if a player leaves the game, all cards that player owns leave as well, and any effects that give the player control of permanents immediately end.
No other card is named in this ruling.
#5July 14, 2017· Wizards of the Coast
No lands that you control will untap during your next untap step, even lands that aren’t tapped as this spell resolves. This includes lands that enter the battlefield after this spell resolves.
No other card is named in this ruling.
#6July 14, 2017· Wizards of the Coast
If more than one spell says that lands you control don’t untap during your next untap step, the effects will all wear off during that untap step. You’ll untap lands you control during your untap step after that one.
No other card is named in this ruling.