Oracle

Enchantment - Aura 

Enchant creature
Enchanted creature can attack as though it had haste.
0: Untap enchanted creature. Activate this ability only during your turn and only once each turn.

Tournooi-info

Legal in: Vintage, Legacy, Commander

Officiele rulings

10/4/2004
If attached to an opponent’s creature, you can untap their creature during your turn.

10/4/2004
Instill Energy’s untap ability will not untap the creature until it resolves. This means other spells and abilities can be used before it actually becomes untapped.

8/1/2005
Any Auras (or other effects) which are on the creature that would cause it to not be untapped (or have a cost to be untapped) during untap step do not in any way hinder or imply a cost to use this card’s ability to untap once during the turn.

Decktips