Edison format ruling
Earthbound Immortal Aslla piscu

Card effect (current official text)There can only be 1 "Earthbound Immortal" monster on the field. If there is no face-up Field Spell Card on the field, destroy this card. Your opponent cannot target this card for attacks. This card can attack your opponent directly. When this face-up card leaves the field, except by its own effect: Destroy as many face-up monsters your opponent controls as possible, and if you do, inflict 800 damage to your opponent for each monster destroyed.
Rulings
- If you control an Earthbound Immortal and no other monsters, your opponent cannot attack you, because they cannot select the Earthbound Immortal as an attack target. (Exception: they can attack with monsters that can attack directly, such as "Submarineroid.")
- If the only Earthbound Immortal on the field is an Equip Spell Card, it is not treated as a monster so you can Summon an Earthbound Immortal.
- If you replace your opponent’s Field Spell Card by activating one of your own, there is a face-up Field Spell Card continuously on the field, so any Earthbound Immortal on the field would not be destroyed.
- If you activate a new Field Spell Card, replacing your own Field Spell Card, there is a gap when no Field Spell Card is on the field, so any Earthbound Immortal would be destroyed.
- If you Special Summon an Earthbound Immortal by chaining "Call of the Haunted" or "Revival of the Immortals" to the activation of a Field Spell Card, even though the Field Spell Card has not resolved when the Earthbound Immortal is Special Summoned as Chain Link 2, the Earthbound Immortal will remain on the field, undestroyed.
- ‘Destroyed by its own effect’ refers to being destroyed if there is no Field Spell Card on the field.
- If a face-down "Earthbound Immortal Aslla piscu" is flipped face-up while another Earthbound Immortal is on the field, the flipped Aslla piscu is destroyed. However, this is not considered as ‘destroyed by its own effect’ so its effect will activate to destroy monsters and inflict damage.
- If a face-down "Earthbound Immortal Aslla piscu" is attacked while there is no Field Spell Card on the field, and the attacking monster destroys it by battle: Aslla piscu is destroyed by battle, it is not destroyed by its effect after that, and when Aslla piscu is sent to the GY as a result of that battle, its effect will activate to destroy monsters and inflict damage.
- If "Earthbound Immortal Aslla piscu" is removed from the field face-down, its effect to destroy monsters and inflict damage does not activate.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Edison forum — sourced change requests get reviewed.