The original ATK of all face-up monsters you control becomes 0, until the End Phase. Each time a monster that had its original ATK reduced to 0 by this effect is destroyed by battle and sent to the GY, draw 1 card.
Monsters with an original ATK that is already 0 are not affected by "Alchemy Cycle". You will not draw a card when they are destroyed by battle.
The effect to draw 1 card starts a Chain.
Monsters Summoned or flipped face-up after "Alchemy Cycle" resolves will not have their original ATK become 0.