This mod makes combat faster, deadlier and more realistic by increasing how much damage everyone take - both you and NPCs.

This mod affects almost everything: physical and magical damage from player and NPCs, falling damage, trap damage...

You can change the damage multiplier by simply changing the difficulty from the game menu.

Novice: x1.0. This is the equivalent of playing on standard Adept difficulty.
Apprentice: x2.0
Adept: x3.0
Expert: x4.0
Master: x5.0
Legendary: x6.0 (added). 

If you wanted to change only the amount of damage you take, but leave your damage dealt constant, try Phitt's "Custom Difficulty" mod:

https://www.nexusmods.com/skyrim/mods/4981