Tengu format ruling
Morphtronic Magnen Bar

Card effect (current official text)● While in Attack Position: Once per turn, if you control exactly 2 other face-up Attack Position monsters, and no additional monsters, this card gains the combined ATK of the other two monsters you control until the End Phase. The other two monsters cannot attack the turn you activate this effect.
● While in Defense Position: Monsters you control cannot attack.
Rulings
- Neither of this card’s effects target.
- If 1 of the monsters that was in Attack Position when this card’s Attack Position effect was activated is switched to Defense Position before the effect resolves, this card still gains the combined ATK of the 2 monsters.
- If another monster is switched to Attack Position before this card’s Attack Position effect resolves, this card still gains the combined ATK of the 2 monsters that were in Attack Position when the effect was activated.
- If 1 of the monsters that was in Attack Position when this card’s Attack Position effect was activated is no longer on the field when the effect resolves, this card only gains the ATK of the remaining monster.
- You cannot activate this card’s Attack Position effect during Main Phase 2.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.