Orzhov Keyrune — ruling 1

Until the ability that turns the Keyrune into a creature resolves, the Keyrune is colorless.

Orzhov Keyrune — ruling 2

Activating the ability that turns the Keyrune into a creature while it's already a creature will override any effects that set its power and/or toughness to another number, but effects that modify power and/or toughness without directly setting them will still apply.

Orzhov Keyrune — ruling 3

Multiple instances of lifelink on the same creature are redundant. Activating the last ability multiple times won't cause you to gain more life.

Orzhov Keyrune : règles, fonctionnement et interactions (MTG)

Orzhov Keyrune 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

: Add or . : This artifact becomes a 1/4 white and black Thrull artifact creature with lifelink until end of turn.

How it works : Orzhov Keyrune

Original English text — Wizards of the Coast / Scryfall

#1April 15, 2013· Wizards of the Coast
Until the ability that turns the Keyrune into a creature resolves, the Keyrune is colorless.
No other card is named in this ruling.
#2April 15, 2013· Wizards of the Coast
Activating the ability that turns the Keyrune into a creature while it's already a creature will override any effects that set its power and/or toughness to another number, but effects that modify power and/or toughness without directly setting them will still apply.
No other card is named in this ruling.
#3January 24, 2013· Wizards of the Coast
Multiple instances of lifelink on the same creature are redundant. Activating the last ability multiple times won't cause you to gain more life.
No other card is named in this ruling.