Paralyze

Oracle Text

Enchant creature

When Paralyze enters the battlefield, tap enchanted creature.

Enchanted creature doesn't untap during its controller's untap step.

At the beginning of the upkeep of enchanted creature's controller, that player may pay 4. If the player does, untap the creature.

Card Rulings

10/4/2004 Paying the cost is optional.
10/4/2004 Paralyze can be cast targeting a creature which is already tapped.
10/4/2004 The creature can only be untapped using Paralyze once per turn.
10/4/2004 Two Paralyzes are not cumulative. Paying either one will untap the creature.
9/16/2007 This is a change from the most recent wording. As was the case in the past, Paralyze itself has the last triggered ability, rather than granting that ability to the enchanted creature.