User blog comment:Tenebraeh/Resummon Gate/@comment-26947994-20160722033327

Assuming that it's equally likely for any of the units to be summoned (so disregard rarity and promotion), you have about a 46.1% chance to summon Azurai. Given that he is a 7* base unit and the rest are 5* minimum, the probability may be lower, even though rates up for Azurai are happening now.

I really don't think you should summon for Azurai, because, let's face it, everyone hates gumi for the summon gate rates. I would say keep your gems until you have like 20 summons, and only summon when absolutely, ABSOLUTELY necessary, for example when you need to replace a role in your team. Gumi (and Alim) will continue to create more and more powerful units, so the later you summon the more powerful units you will get.