I've beaten many centaurs but each time I face a Unicorn it feels impossible. She does SO much damage. Magic worked for a bit but her damage output is just too much.
You only meet a Unicorn if you are an anal virgin. Which is usually in early parts of the game... Facing a Unicorn then is tough. You can trade hits with magic like True Fire, if both hp reaches 0 in the same round you still get the win.
For melee, usually you run out of stability after a few hits and get kited down. Better to just avoid the encounter until stronger.
You get nothing special from defeating a unicorn sadly. If you need to defeat her then trick to fight is, if I remember correctly, skipping first turns of the fight by blocking. That way she will run out of both stamina/stability and arrows after which will make rest of the fight quite easier. Later on with higher perception or agility you are able to simply avoid the fight by default.
