The Test Shard is an exact copy of the game world in which players can test builds, house placements and anything else they would like to test.
Three coloured statues can be found near Prevalia Bank which will allow players to set their skills and spawn any items they would like to test with.
This video is a complete guide to using the Test Shard: https://www.youtube.com/watch?v=SAkHf8OJn9g