Advanced 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.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.