Re: GLC2, the only name I keep hearing again and again is Star Sapphire, which seems pretty logical. Also, I think we'll be seeing Ch'p as some kind of pack in, due to the quick glimpse that was shown at SDCC.
But what I'm hearing re: DCUC17 is that it will be entirely comprised of Rainbow Lanterns/Deputies, to wit:
White Lantern Hal Jordan (w/Black Lantern variant)
Blue Lantern Flash
Violet Lantern Wonder Woman
Indigo Lantern Atom
Orange Lantern Lex Luthor
Yellow Lantern Scarecrow
C&C: Anti-Monitor
If this is true, and from what I'm hearing, it may yet be, I'm really underwhelmed. I can see the logic of a wave that will be out in time to promote the GL movie next year, along with the two GLC waves, and it's got big, well-known A-listers to appeal to Moms and kids, but I personally think the wave is kind of a waste.
As some have suggested, though, it may be a "breather" wave, to allow catch up, since there have been delays on Waves 14 and 15.
The shame is the one character in this category I'd most want, Mera, does not appear to be included.

