As the main ingredient in mutagen decoctions.
Signs are magic spells in the Witcher 3: Wild Hunt. There are five signs in the game – Aard, Igni, Axii, Quen and Yrden, each with a unique effect and upgrade tree. Signs are not a substitute for weapons, but they can be very helpful if you upgrade and use them properly. This guide will show you all the signs present in the game, along with their effects and upgrade benefits.
Using signs will drain your stamina, so keep an eye on your stamina bar whenever you use them. You do not want to run out of stamina during a fight. Fortunately, you will receive a bonus to your stamina regeneration whenever you upgrade a sign skill.