From Brotato Wiki
Triangle of Power is an in-game item that can be bought from Shop or can be found in a Crate. Most Items increase the Stats of the player while some of them provide unique effects.
The Triangle of Power grants you a large amount of Damage for its cost, however it comes with a catch. While you have Triangle of Power, you lose 2% Damage each time you are hit.
The damage resets at the end of a wave, but the item can end up reducing your damage by a lot if you take damage multiple times over the duration of a wave. Self-damage such as Blood Donation or the Character Sick also triggers the effect, and the Triangle of Power should be avoided in those cases.