Tengu format ruling
Alien Skull
Card effect (current official text)You can Tribute 1 face-up Level 3 or lower monster on your opponent's side of the field to Special Summon this card to your opponent's side of the field. If you Special Summon this monster this way, place 1 A-Counter on this card, and you cannot Normal Summon or Set the same turn. (If a monster with an A-Counter battles an "Alien" monster, it loses 300 ATK and DEF for each A-Counter during damage calculation only.)
Rulings
- While you control 2 copies of this card, a battling monster with 1 A-Counter will lose 600 ATK/DEF.
- All of the Ⓤ is one single unclassified effect. Tributing a monster is a cost for this effect. This effect does not start a chain.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.