At the start, nothing comes out. However, you will eventually come face-to-face with four Sluggies: one Black, one Angel, and two Red, backed up by Squire Rels, Those Guys, Not only are they much stronger than before, they're only a taste of what's to come! Hit the base and you will end up with a small mob of Sluggies and three Angelic Sleipnirs, so be careful. The Angelic Sleipnirs spawn 50~53.3 seconds apart.
To beat this stage, you will need to save up money first by stalling the Angel Sluggy. Once you have Bahamut and other strong hitters on the field, prepare for the Sleipnir triple threat. Dragon Cat can be a huge help here (even more so if you happen to have his True Form), but don't use Paris Cat, as she won't even be able to get a single hit off. Try to meatshield your ace in the hole as best you can. Don't forget to bring long-range support with you.