Ultima Summon

A Ultima Summon (アルティマ召喚, Arutima Shoukan) is the method of Summoning an Ultima Card. To Ultima Summon an Ultima Card, you must have an appropriate number of Tags in a monster (gained through effects) and the appropriate monster listed in the Ultima Card's Card Text in the same Monster Zone as the Tags you are using for the Summon. The number of Tags on your side is then divided by the Level of the monster you are using, and that value (rounded down) must be equal to the Hierarchy of the Ultima Card you are attempting to summon. The monster on your field is then banished while the Ultima Card is Summoned in the same Monster Zone as the banished monster. If the Ultima Card is removed from the field, half of the Tags in it's Zone are removed.

Rulings
As Ultima Cards are not monsters, Ultima Summon cannot be negated through cards such as or.