Kanako Vs Marianne

Turn 1 (Kanako)
LP: Kanako 4000 -- Marianne 4000
 * Kanako summons Marshmallon in Attack Position ( 300 Atk /500 Def).

Turn 2 (Marianne)
LP: Kanako 4000 -- Marianne 4000
 * Marianne Sumons Venom Coral in Attack Position ( 800 Atk /100 Def) and uses its effect to place 1 Venom Counter on Marshmallon.
 * Venom Coral attacks Marshmallon. (Kanako 4000 ↓ 3500)
 * Marianne sets 2 magic or trap cards.

Turn 3 (Kanako)
LP: Kanako 3500 -- Marianne 4000
 * Marianne activates Paralytic Venom, preventing monsters with Venom Counters from changing battle position.
 * Kanako summons Elf Swordsman in Attack Position. ( 1400 Atk /1200 Def)
 * Elf Swordsman attacks Venom Coral. (Marianne 4000 ↓ 3400)
 * Venom Coral's effect activates. Since it was destroyed by Battle, Marianne summons another Venom Coral from her deck in Attack Position ( 800 Atk /100 Def).
 * Marianne activates the effect of Venom Coral, placing 1 Venom Counter on Elf Swordsman.
 * Kanako sets a Magic or Trap card.
 * Marianne activates Sand Tornado during the End Phase, destroying Kanako's set Calm Magic and setting 1 magic or trap card from her hand.

Turn 4 (Marianne)
LP: Kanako 3500 -- Marianne 3400
 * Marianne releases Venom Coral to summon Venom Puffer in Attack Position ( 1600 Atk /1900 Def) and uses its effect to place 1 Venom Counter on Elf Swordsman.
 * Venom Puffer attacks Elf Swordsman. Due to Venom Puffer's effect, Elf Swordsman loses 400 ATK for each Venom Counter on it. Elf Swordsman ( 1400 ↓ 600 Atk /1200 Def)
 * Marianne activates Energy Siphon during the Damage Step, increasing Venom Puffer's ATK by the amount of ATK lost by Elf Swordsman. Venom Puffer ( 1600 ↑ 2400 Atk /1900 Def)
 * Venom Puffer destroys Elf Swordsman. (Kanako 3500 ↓ 1700)
 * Venom Puffer's effect activates. Since it destroyed a monster with Venom Counters on it by battle, it can attack one additional monster.
 * Venom Puffer attacks Marshmallon, reducing its ATK to 0 due to the Venom Counter on it. (Kanako 1700 ↓ 0)

Marianne wins the duel.