The first thing to note is that the colored border continues on the bottom of the cards, whereas newer cards only have this colored border on the top and sides
Just look at the last set and how green plays with +1/+1 counters and they'll almost certainly work beautifully
Murktide is also a graveyard-dependant threat this means that Relics of Progenitus, Rest in Peace and other graveyard hate, that are typically decent against blue-based decks, can stop this dragon from being a good threat or to be castable at all
Now for the Hour of Glory Erebos, God of the Dead | Illustration by Peter Mohrbacher Oh wait, no, the Hour of Glorys a bad thing
Yes, you can have two of the same emblem active at once
Greater Auramancy - Keeps your pillow fort safe from removal