Geralt can cause and sustain temporary effects before and during combat. Potions provide the buffs that make him sturdier and more lethal in battle, oils can improve his swords, and Quen can shield him from harm of almost any form. Igni can set targets on fire. Aard can knock foes flat, setting them up for executions. Yrden can slow any victims within its range.
Combat may often cause unpleasant temporary debuffs on Geralt: sword strikes and the claws of monsters can cause bleeding, or inject poisons. Fires in the environment or used by enemies can cause burning damage over time. Water Hags can throw projectiles that temporarily stun Geralt. Sometimes, the environment itself is filled with noxious or flammable gasses that choke Geralt, unless he burns them away with Igni or clears the air with Aard. Extreme temperatures in the world can still hurt a witcher.
Armor and armor enhancements can help mitigate some of these temporary effects. Every piece of armor has individual defense ratings for elemental damage, poisoning, bleeding, burning, and damage from monsters. Some armor might have special effects that can further enhance Geralt’s resistances to debuffs. For things that stun or knock Geralt to the ground, Quen is your chief defense.