From the Super Mario Wiki
The Invincibility Leaf (also called Invincible Super Leaf) is a power-up that first appeared in Super Mario 3D Land. This power-up is very similar to the Super Leaf, but with added invincibility.
Super Mario 3D Land
In Super Mario 3D Land, it only appears after Mario loses five lives in a level that is not already completed. It will not appear when re-visiting a completed level or a Special World level. This means Luigi cannot obtain it in that game unless the player skipped any levels in the normal worlds (for example, by using a Warp Zone). Touching it will give Mario a shining white and golden Tanooki Suit, making him White Tanooki Mario, and it will make him invincible, as the Star also does, but the invincibility lasts for the entire level.
New Super Mario Bros. 2
The Invincibility Leaf returns in New Super Mario Bros. 2, but changes Mario into White Raccoon Mario instead of White Tanooki Mario. As with Super Mario 3D Land, one only appears after Mario loses five lives in any given level, with the exception of the Cannon levels. As White Raccoon Mario, the P-Meter fills up faster than as normal Raccoon Mario, and Mario has the ability to walk/run on water, like Mini Mario. The power-up will last for the entire level and will revert to normal Raccoon Mario/Luigi upon completion. Its Assist Block will remain in the level until the player beats it without using it. It can also be used in Coin Rush mode, where the Assist Block is available from the beginning of the level.
The Invincibility Leaf cannot be replaced by any power-up items, including the Gold Flower and Mega Mushroom. However, the Star item can still be used while the Invincibility Leaf is in effect. To obtain the secret exits and unlock the hidden levels, the player must clear the level without using the Invincibility Leaf.
Super Mario 3D World
The Invincibility Leaf also appears in Super Mario 3D World, referred to as the Invincible Super Leaf on the website. It functions the same way as in Super Mario 3D Land. After completing a level with it, the player will revert back to Tanooki Mario, Luigi, Princess Peach, Toad, or Rosalina.
Names in other languages
||Hoja de Invencibilidad