Here is the full list of all 19 Peasant Knight achievements.
Finish a level right before the lightning hits.
Complete 12 levels.
Complete all death challenge levels.
Get as close as possible to an errupting flame pit without touching it.
Get as close as possible to a saw without touching it.
Walk on lava for as long as possible without burning.
Complete a level while constantly jumping.
Complete 3 levels in a row without dying.
Complete 5 levels in a row without dying.
Complete 10 levels in a row without dying.
Die 25 times to flame pits.
Get crushed 25 times.
Defeat an orc.
Defeat the skeleton.
Defeat the Mortar Orc.
Defeat the evil wizard.
Complete 10 levels in journey mode with one or more friends.
Complete 3 race or marathon games with one or more friends.
Complete 8 race or marathon games with one or more friends.