Cannot be Normal Summoned/Set. Must be Special Summoned with "A Deal with Dark Ruler" and cannot be Special Summoned by other ways. This card can attack all monsters your opponent controls once each. During each of your End Phases, this card loses 500 ATK.
Berserk Dragon can only be played with A Deal with Dark Ruler. Additionally, Berserk Dragon can also fulfill the condition for activating A Deal with Dark Ruler to summon another Berserk Dragon.
Since you need a level 8 or higher monster to be destroyed to activate a Deal with Dark Ruler, the best candidates are level 8 or higher monsters that can be special summoned or easily brought out on the field.
Yes I had 500 LP left and my opponent was playing jurrac Deck and has 3 monsters and I have no monsters and after Phoenix was destroyed by Fire king Island and sent to GY I summoned Berserk & attacked all his monsters & a monster effect was activated to put another 2 tokens on his field which I attacked also with Berserk so Totally I attacked 5 times in the same turn & with Barong I Finished him