Elixir Collector is one of the unique buildings in Clash Royale. It doesn’t deal any damage but generates elixir instead. Most players used the Elixir Collector if they have high elixir cost decks. Ideally it is placed behind the Arena Tower to benefit from its full duration. However, if facing building aggressive troops like Hog Rider, you can place it defensively by putting it in front of your Towers. Take note that it has lower health compared to other buildings.
The Elixir Collector shines greatly during the sudden death overtime because of the double elixir generation. You can deploy high cost unit continuously, making your opponent unable to counter many strong troops at the same time.