Tengu format ruling
Dark-Eyes Illusionist

Card effect (current official text)FLIP: Target 1 monster on the field; it cannot attack while this card is face-up on the field.
Rulings
- You can select a face-down monster.
- When a face-down Dark-Eyes Illusionist is attacked and destroyed, its effect does not activate.
- If Royal Command is actived after Dark-Eyes Illusionist's effect resolves, Dark-Eyes Illusionist's effect is negated.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.