Tengu format ruling
Sea Koala
Card effect (current official text)Once per turn: You can target 1 monster your opponent controls; change its ATK to 0 until the end of this turn. You must control a Beast-Type monster (other than this card) to activate and to resolve this effect.
Rulings
- If an effect is chained to Sea Koala's effect that removes every other Beast-Type monster from your side of the field, the effect of Sea Koala disappears.
- After making the ATK of 1 of your opponent's monsters 0, the ATK of the opponent's monster remains 0 until the End Phase. even if every other Beast-Type monster you control is removed from the field.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.