So... If I'm correct, then creatures buffed with Adrenaline don't just attack more times per one turn. When buffed, a creature lives multiple turns in the time of one turn. For example, if a Brimstone Eater is buffed with Adrenaline, it lives four turns in the time of one turn; that's the reason why it produces 4 Fire per turn.
OK, this card seems officially broken now...