Card Rulings:Grave Fusion

As long as all the Fusion Monsters are Zombie-type, you can Fusion Summon more than one Fusion Monster with this card. You must chose the number of Fusion Monsters to summon when you activate this card. If the spell is activated corectly, you MUST Fusion Summon the selected monsters (unless a full field prevents you from Fusion Summoning, which may happen with certan spells, traps, and monster abilities).

So far, this is the only card which alowes the Fusion Summon of multiple Fusion Monsters in the game.