Edison format ruling
Mass Hypnosis
Card effect (current official text)Activate only while you control an "Alien" monster. Select and take control of up to 3 of your opponent's monsters that each have an A-Counter(s) on them. This card is destroyed during the End Phase of the turn it is activated.
Rulings
- You can only select as many monsters with A-Counters as you have empty Monster Card Zones.
- If a monster you control with the effect of Mass Hypnosis is flipped face-down, then you will keep continue to control it, even though it no longer has A-Counters and even if Mass Hypnosis is removed from the field.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.