The Beetle is one of the absolute most dangerous field enemies on the map. There are mini versions of this enemy which do not attack, and can drop 50 gold.
Attacks forward with an extremely fast lunge.
Lunge is too fast to dodge, even with Sprint. Instead, stand just out of reach of the beetle and wait for it to lunge, then attack it once or twice, then run out of range again. This can be a difficult timing to get down, and each miss means taking huge damage from the Lunge. The Beetle also has huge max HP.