
In the Definitive Edition, there is an option in the game's settings labeled "Safe Delete", where attempting to kill an important unit will prompt a message asking if the player wants to proceed in killing the unit. Main article: Heroes (Age of Empires II) Trivia
Note that some hero units appear only in specific campaign scenarios, and are not seen in the Scenario Editor. Heroes are special units that also appear in campaigns and are available in the Scenario Editor. Some units are not even available in the Scenario Editor (as of patch 5.1), but are still found in the game files. There are also many units that appear in campaign scenarios only and/or are available in the Scenario Editor.
Caravel → Elite Caravel ( Portuguese only). Turtle Ship → Elite Turtle Ship ( Koreans only). Longboat → Elite Longboat ( Vikings only). Demolition Raft → Demolition Ship → Heavy Demolition Ship. Fire Galley → Fire Ship → Fast Fire Ship. The Castle is a strong fortification and also provides unique units and technologies. The Market is the center of trade and trains the only available land trade unit. Bombard Cannon → Houfnice (the latter Bohemians only). The Siege Workshop trains and upgrades siege weapons. Xolotl Warrior ( Aztecs, Incas, and Mayans only). Steppe Lancer → Elite Steppe Lancer ( Cumans, Mongols and Tatars only). Tarkan → Elite Tarkan ( Huns only after researching Marauders).
Battle Elephant → Elite Battle Elephant ( Burmese, Khmer, Malay, and Vietnamese only). Camel Rider → Heavy Camel Rider → Imperial Camel Rider (the latter Indians only). Scout Cavalry → Light Cavalry → Hussar → Winged Hussar (the latter Lithuanians and Poles only). Genitour → Elite Genitour ( Berbers and allies only). Skirmisher → Elite Skirmisher → Imperial Skirmisher (the latter Vietnamese and allies only). The Archery Range trains and upgrades archers. Huskarl ( Goths only after researching Anarchy). Condottiero ( Italians and allies only). Eagle Scout → Eagle Warrior → Elite Eagle Warrior ( Aztecs, Incas, and Mayans only). Militia → Man-at-Arms → Long Swordsman → Two-Handed Swordsman → Champion. The Barracks trains and upgrades infantry. Flemish Militia ( Burgundians only after researching Flemish Revolution). The Town Center is the most important of all buildings, and trains the most important unit. Nine different buildings can train units. To see which civilization can train which units, see technology tree. Note that not all of these units are available to all civilizations, unless the All Techs option is checked. The following units are available in any regular game.