Tengu format ruling
Cyber Eltanin

Card effect (current official text)Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by banishing all LIGHT Machine monsters from your field and GY. This card's ATK/DEF become the number of monsters banished for its Special Summon x 500. If this card is Special Summoned: Send all other face-up monsters on the field to the GY.
Rulings
(C) This card cannot be Normal Summoned or Set. (S) This card cannot be Special Summoned except by removing from play all face-up LIGHT Machine-Type monsters from your side of the field and your GY. (1) This card's ATK and DEF are equal to the number of monsters removed from play for its Special Summon x 500. (2) When this card is Special Summoned, send all other face-up monsters on the field to the GY.
- The (C) Summoning Condition cannot be negated.
- The (S) Special Summon Effect is the only way to Special Summon this card.
- This Summon does not start a chain.
- This card CANNOT be Special Summoned from the GY / removed from play area.
- Only LIGHT-Attribute Machine-Type monsters (and Tokens) are removed from play as a cost.
- Face-down LIGHT-Attribute Machine-Type monsters are not removed from play.
- You can Special Summon Cyber Eltanin even if you only have 1 LIGHT-Attribute Machine-Type monster on your field and/or in your GY.
- The (1) Continuous Effect effect applies so long as it is face-up on the field.
- The ATK/DEF become 0 if it is flipped face-down, leaves the field, or Skill Drain negates its effects.
- The (2) Mandatory Trigger Effect activates in the Summon response timing.
- This effect does not affect face-down monsters.
- This effect 'sends' monster cards to the GY; it does not 'destroy' them.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.