Text (5th/7th/8th+errata): You may tap or untap target artifact, creature, or land. [Oracle 2006/10/01]
The opponent gets a chance to use the card being Twiddled in response to this spell if they so wish and if the card's ability is legal at the time. [D'Angelo 1994/06/01]
Any cards which might trigger off a card becoming tapped will trigger. Thus, a Psychic Venom on a land that becomes tapped will cause 2 damage. [D'Angelo 1995/03/12] Similarly, if the card itself triggers on its own tapping, such as City of Brass, the ability will still happen. [D'Angelo 1995/04/12]
The decision to tap or untap is made on resolution. [D'Angelo 2000/03/03] This is not a modal spell.
The choice of target gives free range of lands, creatures, and artifacts. You do not lock in on one type as a casting decision. If the spell is Forked or redirected, the type is not fixed. [Duelist Magazine #8, Page 50]
Twiddle to tap can target a tapped card, and Twiddle to untap can target an untapped card. [Duelist Magazine #5, Page 23]
This is not a toggle effect. If you use Twiddle to tap a card and before it takes effect your opponent taps it, Twiddle will not untap the card. [bethmo 1994/04/01]
