Blazing Heart

The Blazing Heart is a craftable Permanent Power-up that can also be found from Underworld when mined. When used, it permanently increases the player's health capacity by 10, adding a red heart and covering 2 hearts with blazing hearts to the player's health bar, while also restoring 10 health. Blazing Hearts are consumed upon use.

Up to 10 Blazing Hearts can be used, increasing health capacity to 400 (5 hearts). Additional Blazing Hearts can no longer be used at that point, and attempting to do so will not consume the item. Extra Life Crystals/Blazing Hearts acquired thereafter can either be sold for coins or used to craft Heart Lanterns/Blazing Braziers.

After a world converts to Hardmode, and after the 400 health maximum is reached from consuming Life Crystals and Blazing Hearts, Dazzling Hearts can then be used to increase health capacity further, to a maximum of 450 (10 Dazzling Hearts) followed by Life Fruits, to a maximum of 500 (10 Life Fruits).

Trivia

 * This item, as well as the new heart system as a whole, was originally suggested by Snickerbobble on Terraria Community Forums.
 * Despite not appearing on the achievements screen in-game, using this will give you the "Get A Life" Achievement.
 * Even though the item forbids the use of Life Crystals at 350 HP, Life Crystals can still be used via the Autopause glitch, making the usage of the Blazing Heart optional.