Edison format ruling
Criosphinx

Card effect (current official text)When a monster is returned from the field to the owner's hand, the owner of the returned monster selects and sends 1 card in their hand to the Graveyard.
Rulings
- If multiple monsters are sent to the hand simultaneously (such as with "Guardian Sphinx"), the effect of "Criosphinx" only activates once, so only 1 card is sent to the GY.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.