I want to be sure about this. Can it be or can't it not summoned without effect of Clock Tower Prison? Card says "if this card was special summoned by effect of Clock Tower Prison" So I assume its possible but I want to be sure.

Note the text...

D. Hero Dread Guy/"Dreadmaster"
Dark/Warrior/8/?/?
If this card was Special Summoned by the effect of "Clock Tower Prison", destroy all monsters on your side of the field except the ones that include "Destiny Hero" in their card names, then you can Special Summon up to 2 monsters from your Graveyard that include "Destiny Hero" in their card names. During the turn this card is Special Summoned, monsters on your side of the field that include "Destiny Hero" in their card names cannot be destroyed, and all Battle Damage inflicted to the controller of this card becomes 0 during battle involving monsters on your side of the field that include "Destiny Hero" in their card names. The ATK and DEF of this card are equal to the combined original ATK of all monsters on your side of the field (except this card) that include "Destiny Hero" in their card names.


It only means for its FIRST effect (destroying all non-D. Hero monsters and Special Summoning up to 2 D. Hero monsters from your Graveyard), you would need to Special Summon it specifically via Clocktower of Seclusion/"Clock Tower Prison".

Rule:

"Destiny Hero - Dreadmaster's" second sentence is applied if he is Special Summoned by any method, not just by the effect of "Clock Tower Prison".

That means it CAN be Special Summoned like any other monster, but you WON'T get the first effect unless it was specifically via Clocktower of Seclusion/"Clock Tower Prison", but you would still get the rest of the effect. Just note that the ATK/DEF section does not care at all about Special Summoning.

More to the point, as per my article entitled "Master of the Thriller" in the News/Announcements section (read up if you're running D Hero).

The first effect will only be activated if special summoned by Clock Tower.

The second effect (no D Heros can be destroyed by effect or battle) happens ANY TIME its special summoned (call, Fear Monger, Reasoning, etc.

The third effect (atk/def) happens any time its on the field obviously.

"Destiny Hero - Dreadmaster's" second sentence is applied if he is Special Summoned by any method, not just by the effect of "Clock Tower Prison".

...pretty much points all that out there.

well, i think the question being asked was if clock tower prison was the only way to summon him (since there was no mention of his effects other than that in the question)

and as your answers indirectly suggested, dreadmaster has no special summon requirements at all. infact he has no method for special summoning him in his text. he can be normal summoned, set, or special summoned in any appropriate way.

he is comparable to say dark magician of chaos and dedication through light and darkness. dedication is simply a card that allows you to special summon a specific monster. it doesn't mean that its necesary to use it to summon him. or comparable to hand of nephthys and the sacred phoenix. you don't have to use hand to summon the phoenix. the same is true for dreadmaster and clock tower prison.

Yep..hence the "If" in his text, meaning if he is Special Summoned in that specific way, but nothing else stating "This card can only be Special Summoned by..." or "This card cannot be Special Summoned except by..."

Just giving you extra options and, I guess, trying to "persuade" people to Special Summon him that way. People try too, considering it gives you pretty good side-effects as well.