Is there any way to increase your permanent health in terraria?

Solution 1:

This guy in your video was using the Calamity Mod. You'll have to download the mod before you can have diamond hearts. (was it Chippy?)

To increase your max HP in base terraria, you have 3 options:

1. Find a Life Heart underground, and use it. Increases max HP by 20, to 400 cap.

2. Find a Life Fruit in the Underground Jungle, post-Plantera (or anytime on mobile, old-gen console, and 3DS). Increases max HP by 5, 500 cap.

3. Use a Lifeforce potion. This is a temporary potion that increases max HP by 20%.

Edit: About the diamond hearts:

https://terraria.gamepedia.com/Health

https://calamitymod.gamepedia.com/Permanent_Power-ups