While the Red Devil itself does not cause much contact damage, its trident attack is capable of dealing large amounts of damage even to players in Hallowed armor, Chlorophyte armor and Turtle armor. The tridents are similar to the Demon's scythe attack, but do more damage and do not accelerate.
The Red Devil is immune to the On Fire! debuff.
- To defeat it, attack only while it charges his tridents. While he shoots, focus on dodging only, as receiving more than 4 hits will probably kill you.
- If you defeat any of the three mechanical hardmode bosses before hardmode is enabled (through use of the appropriate summon items), this will allow for the Red Devil to spawn at any time. If you don't want them to appear, avoid fighting the hardmode bosses pre-hardmode.