What is the Spell card that gives Harpie Lady Sisters 2700 ATK?

The Spell card that gives Harpie Lady Sisters 2700 ATK is called "Harpie's Feather Duster".

Here's how it works:

* Harpie's Feather Duster is a Spell card that destroys all Spell and Trap cards on the field.

* When it is activated, Harpie Lady Sisters gains 700 ATK until the end of the turn.

* Since Harpie Lady Sisters' base ATK is 2000, Harpie's Feather Duster boosts their ATK to 2700.

This effect is a powerful way to gain an advantage in battle and often used in Harpie decks.