You can only activate 1 card with this card’s name per turn.
(1) When your opponent activates a monster effect while you control a “Therions” monster: Activate 1 of these effects, OR, if you have “Endless Engine Argyro System” in your GY, you can activate both, in sequence;
● Negate that effect.
● Banish that monster.
Atom 1.0
