The next limited dragon has arrived and it needs 1 specific parent plus some elements in its breeding pair.
ARMAMENT + Fire + Earth
The Armament dragon is already sharing the fire element; along with light and metal; so we can breed with the earth hybrid with the shortest breed time.
The 4 elements mean Rainbow, Aurora and Double Rainbow are possible, which gives 16.13 hours as the average fail time. 4.25% chance means 16 attempts will give you a 50/50 shot at getting