At the end of the Damage Step, if this card battled a Warrior or Spellcaster-Type monster: Destroy that monster.
Rulings
Individual Card FAQs
If "Ryu Kokki" battles with "Dark Magician of Chaos", "Ryu Kokki" is destroyed and removed from play by "Dark Magician of Chaos"' effect, and "Dark Magician of Chaos" is removed from play because it is destroyed by "Ryu Kokki"'s effect and removed by its own effect.
DARK|
Level 6|[ Zombie / Effect ]
ATK 2400|
DEF 2000