Superheavy Samurai Battleball

If all monsters you control are Superheavy Samurai monsters, and you have no Spell/Trap Cards in your Graveyard: You can target 1 face-up monster your opponent controls that has a Level; send both it and this card from the field to the Graveyard, then Special Summon from your Extra Deck 1 Superheavy Samurai Synchro Monster whose Level equals the total original Levels of those 2 monsters in the Graveyard. (This Special Summon is treated as a Synchro Summon.) You can only use this effect of Superheavy Samurai Battleball once per turn.