The 2021 camping event is underway, and for a change, the 3 permanent event dragons have only 2 elements. This allows us the freedom to introduce a third element when cloning, to decrease average fail time, without introducing the dreaded rainbow fails. The order I recommend you try for them is …
Aperture Dragon (cold/water hybrid)
The dragon made from those elements, with the shortest breed time is Ice (or Iceberg).
This one has a 10% clone chance, so just 7 tries required for the 50/50 chance. The average fail time