Extra Dimension

|Extra Dimension|???|????|Spell Card|Spell||Field|||When this card is activated; destroy all monsters on the field that were Special Summoned from the Extra Deck, also they cannot be Special Summoned from the Graveyards by card effects. Neither players can Special Summon monsters from their Extra Deck. If this card would leaves the field: Either players can sent 1 monster from their Extra Deck instead. All monsters either players controls gain 100 ATK for each monsters in their opponent's Graveyards that were Special Summoned from the Extra Deck.|

scheath on a cardmaking rampage

It's a Sidedeck card, really not much to say. The difficult thing is if a new field spell enters, would that count as "if this card would leave the field" ?