I got this bit of code here:
IEnemy[] Enemy = new IEnemy[2];
Enemy Goblin = new Enemy("Goblins", "Looks dirty and not so friendly", 100);
Enemy[0] = Goblin;
Goblin.EnemyEncounter();
Sounds like you need to use a parent class that has a list of other entities.
Something like:
var world = new World();
world.Enemies.Add(new Enemy{type="Goblin"});
world.Heros.Add(new Hero{name="Bart Simpson"});
Etc...
World would need to have collections defined for each type, such as: Enemies, Heros, Vehicles, Treasure, etc...