

Out of all the legendary and divine dragons, only the Pixel Dragon has got lower health points.

228 base health isn't so great and considering health points, the Furnace Dragon looses to many epics, and even a rare Rust Dragon can reach 240 health (having humble 56 base attack damage). I don't need to remind you that skills' power scales with the base attack damage, so it's more important statistics than the base health points, do I? And Furnace's base attack damage is actually in top 7 dragons in the game available ever! (Besides 3 mentioned above divines, there are also 3 legendaries with exactly the same attack damage). There is no legendary dragon that has got higher attack damage than the fully awoken Furnace Dragon, and only a few divines: Zeus (82), Taiyi Zhenren (83) and Chang'e (85).

Thus, if you don't have needed dragons, it may be better idea to try another combination than to rush obtaining Bloom or Beetle. So, in my opinion, obtaining dragons required for the preferred combination can be even as hard as obtaining the Furnace Dragon itself. Furthermore, the Beetle Dragon requires the breeding den upgraded at least to level 4, the Venom Dragon enchanted to level 3 or higher and the Orange Dragon enchanted to level 2 or higher as parents. The Bloom Dragon requires the breeding den upgraded at least to level 2 and enchanted Agave and Cloud Dragons as parents. Both Bloom and Beetle Dragons are only available through enchanted breeding. The Kangaroo Dragon is an epic card dragon, so it's very unlikely for any new player to have it. Both Ash and Chef Dragons are limited-time and we haven't been given a chance to obtain any of them this year. It is possible that you aren't able to use No. 1, and if you aren't going to be able to play for the next 6 hours or longer, choose the combination No. 1 have more possible outcomes, that have lower breeding times, so if you are going to be able to rebreed your dragons in few hours, choose the combination No. If you are lucky to have needed dragons for both of those combinations and have the luxury of choosing between those combinations, the reasoning is the same as above: the combination No. If you already have got the Sunflower Dragon, combinations No.
