Aquaman: This issue goes a bit too fast for my tastes. We find out a WHOLE LOT of stuff, but it's almost like a laundry list. Granted, it's supposed to feel like it's happening too fast from the point of view of the characters, but still.
Atlan shows up, tells Arthur how proud he is of his son, then zaps the gang out of Netherspace (pissing off the Others in the process, but hey, he's Atlan, he doesn't care). Turns out Arthur Jr. has the same problem Immortus's son did, rapid aging in the wrong reality. AJ has to go back to Netherspace to survive, and Mera follows, being conveniently written out of the plot for the moment. Orin tries to stop them, but his hook hits the wall and he gets zapped by a plot device.
Meanwhile, Thanatos's declaration of war is being taken seriously, at least by Admiral Strom, who knows all too well what Aquaman (or a replacement) can do to the surface world, even if he *isn't* an ancient Atlantean mage in disguise.
Back in the depths, Arthur recovers from his zap and Knows Everything, but is too hyper about it to really explain at first. Then Tiamat (no relation to the one in War of the Gods, as far as I know, but she claims to be the real thing) comes out and attacks Arthur and Dolphin as the ship they're in rises from the ground. (Oh, another meanwhile during this, Koryak's group discovers a strange pod...ohmygod! Jean Grey! No, not really.)
Apparently the DC version of Fin Fang Foom's race, Tiamat's race has plans for Earth, but her ship has decided to interfere. At first it just sent dreams to Arthur (yep, that's where they came from) but once Arthur 'interfaced' with it using his harpoon, it could give him direct feed. There's a medium-length fight with the Simonson-designed Tiamat before Arthur defeats it handily.
Atlantis rises atop a floating stone sphere last seen in the tunnel paintings last issue, and Strom realizes it's happening ahead of schedule. As a parting taunt, the crispied Tiamat tells Arthur's he's no more human than she is, and in the final scene we get a pretty good idea what she means by that. For who should emerge from the pod but Kordax, first possessor of the Hard Water power, and scaly enough to be a halfway point between Tiamat and Arthur.... Oh, and he has his left hand replaced by a sword.