User blog comment:Pigeonholed/Units to evolve with Sphere frog?/@comment-76.201.71.43-20141030153539/@comment-25251916-20141031034159

Even if Raid Battle does come, sphere frogs are still rare and hard to come by. It'll take some time to be able to obtain a considerable amount of sphere frogs. For the mean time, I would honestly wait to sphere frog when you know for sure you'll be constantly using that unit in most of your team compostions.

For example, you'll obtain the most use of it by healers such as Rashil but I would still hold onto it in case if you summon a better premium healer. Otherwise, Duel GX or in his 6* form Duel SGX can reap more benefits at the moment for you. Duel SGX will be considered your best unit because of his coveted crit chance buff and dark element buff. He is still viable throughout the game sicne he does provide the best crit buff in the game.

At the moment, there is only 4 sphere frogs that can be obtained. But anyways to wrap this up, save your sphere frog until you get a mentionable summon, otherwise you can use it on any other unit that you like using a lot.