Danger Zone
Danger Zones are stage hazards that appear in Smash Run in Super Smash Bros. for Nintendo 3DS and in some stages in Super Smash Bros. for Wii U. Characters who hit them will either take damage or be instantly KOed.
Danger Zones are one of only three ways to be KOed without crossing a blast line, the other two being depleted hit points in Stamina Mode and being crushed.
In Super Smash Bros. for Nintendo 3DS
Danger Zones appear Smash Run in the "Run" and "Climb!" final battles, placed throughout the course. If a fighter hits one, they are instantly KOed and are revived further back/down in the stage. They disappear after being hit once, allowing other players to more easily traverse the stage.
In Super Smash Bros. for Wii U
In The Great Cave Offensive, Danger Zones are placed throughout the stage. If a fighter makes contact with one, they will take heavy damage and knockback, but if they had over 100% damage at the time, they will be instantly KOed without ever passing the blast lines. If the KO property belongs to another fighter when this event occurs, that fighter gains credit for the KO.
Danger Zones can also be added in the game's Stage Builder. All Danger Zones in both the Stage Builder and The Great Cave Offensive appear as noticeable red-orange areas resembling lava.
Danger Zones are also found inside Master Fortress during the Master Core battle at the end of Classic Mode, more prominently during the second wave than the first. These take the form of either subtle yellow outlines on the walls or as more expansive pools of acid resembling those found on Brinstar. Like in The Great Cave Offensive and the Stage Builder, touching one with 100% damage or lower will inflict 25% damage and high knockback, but touching one with over 100% damage will instantly KO the player.