Advanced format ruling
Destiny HERO - Dreadmaster
Card effect (current official text)If this card is Special Summoned by "Clock Tower Prison": Destroy all monsters you control, except "Destiny HERO" monsters, also, after that, you can Special Summon up to 2 "Destiny HERO" monsters from your GY. After this card is Special Summoned, for the rest of this turn, "Destiny HERO" monsters you control cannot be destroyed, also you take no battle damage when they battle. The ATK/DEF of this card are equal to the combined original ATK of all other "Destiny HERO" monsters you control.
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.