Umbral Mantle

Text:

Equipped creature has ", {Q}: This creature gets +2/+2 until end of turn." ({Q} is the untap symbol.)
Equip

Rulings:

• 5/1/2008 If the permanent is already untapped, you can’t activate its <img src="/Handlers/Image.ashx?size=small&amp;name=untap&amp;type=symbol" alt="Untap" align="absbottom" /> ability. That’s because you can’t pay the “Untap this permanent” cost.
• 5/1/2008 If a creature with an <img src="/Handlers/Image.ashx?size=small&amp;name=untap&amp;type=symbol" alt="Untap" align="absbottom" /> ability hasn’t been under your control since your most recent turn began, you can’t activate that ability, unless the creature has haste.
• 5/1/2008 When you activate an <img src="/Handlers/Image.ashx?size=small&amp;name=untap&amp;type=symbol" alt="Untap" align="absbottom" /> ability, you untap the creature with that ability as a cost. The untap can’t be responded to. (The actual ability can be responded to, of course.)