User blog comment:Arkxiah/These summons recently/@comment-31903729-20170618233452

You'll collect new Omni units over time, best to try not to get caught in the "there's a new unit" trap. As other commentors have mentioned, Resummon Gates, Omni Gates, and Unit-of-Choice events are your best chances to get some of the more recent units. The Omni Unit Era pool is diluted with the previous era's batch of units. Alpha's batch (The start of the 7star area) all the way up to the current batch. That's approximately 2 years worth of units in that pool, so there's far from a slight chance of getting lucky to get a new. I've faced the same problem since Kulyuk was released.