Advanced format ruling
Clock Tower Prison
Card effect (current official text)Once per turn, during your opponent's Standby Phase: Place 1 Clock Counter on this card. While there are 4 or more Clock Counters on this card, you do not take any battle damage. If this card with 4 or more Clock Counters is destroyed and sent to the GY: Special Summon 1 "Destiny HERO - Dreadmaster" from your hand or Deck.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.