Dominus of Fealty — ruling 1

If you already control the targeted permanent when the ability resolves, you still need to choose whether or not to apply the effect. If you choose to apply it, the permanent untaps and gains haste. If you don’t, it doesn’t.

Dominus of Fealty : règles, fonctionnement et interactions (MTG)

Dominus of Fealty 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

Flying At the beginning of your upkeep, you may gain control of target permanent until end of turn. If you do, untap it and it gains haste until end of turn.

How it works : Dominus of Fealty

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
If you already control the targeted permanent when the ability resolves, you still need to choose whether or not to apply the effect. If you choose to apply it, the permanent untaps and gains haste. If you don’t, it doesn’t.
No other card is named in this ruling.