Name of 90s first person shooter, doom-like, drink potions to mutate into different creatures with different skills, it changes also view to b/w or blurred etc.

I can't remember the name of this old PC game from the 90s I played as a kid. It was a first person shooter like doom with a magician theme. The map was mostly outside in forests or gardens. As a player you could shoot with a magic stick / wand but there were also potions you could drink. It you would mutate you into different creatures, this would change your vision (e.g. black and white or blurred, etc.) depending on the potion and every creature had it own special powers. One had strong arms to beat your opponents I think.
Can't remember the name or find any screenshots, maybe someone played it too. It wasn't too popular.