I really want to build death and taxes, but I guess it makes zero sense to pursue the deck till Eternal Masters is out as there's a nonzero chance that literally the entire deck shows up in the set.
The effect of eternal masters is all guess right now. Could do any thing from generating insane interest in the format spiking cards past even pre-reprint numbers or it could crash prices once people realize they can't do much with their opened forces unless they buy $400 blue duals. If Port and/or Karakas isn't reprinted they could spike. It's really not a great time to try and get into legacy or be building new decks.
G/R should beat this, right? World Breaker + Return.
Modern is absurd. It's clear eldrazi is the best deck so the real format is metagaming your eldrazi list for other eldrazi lists.