Swallow Flip is a card that first came out in Raging Battle, people never paid any attention to it, but as I am about to show its an awesome side deck card that deserves at least two spots in your side deck
What make a good side deck card? the ability of a card to shut down a lot of different decks. and that is exactly what this card does.
Negate the activation of an Effect Monster's effect that activates when a monster is Special Summoned (including itself), and destroy it.
As you can see this card is very similar to the card pulling the rug but it also activates when a different monster is special summoned for example King Tiger Whangu
This card is also a counter trap meaning, there are not many cards that can get around this card except other counter traps.
Monster u can use them against if they are special summoned
Elemental Hero Stratos
A lot of Synchro Monsters you can use them against
Black Rose Dragon
This are just of the few of the top monsters being used, Im sure you will encounter other decks that this card will help you against