If you are base Green or White in P1, for example, tabling a Murasa Rootgrazer should be enough for you to slide into GW
However, as the format warped around Gholdengo ex with the release of Black Bolt & White Flare , a handful of players correctly identified Gholdengos popularity and were rewarded with favorable matchups en route to top finishes
Having Emrakul, the Aeons Torn or any of the other original Eldrazi Titans from Rise of the Eldrazi helps your postboard matchup against the annoying and surprisingly powerful Dimir Mill deck
That's what happened here
The biggest hurdle just tends to be the price tag
What makes "Domain Of The True Monarchs" really good is the Floodgate effect that when its controller has no cards in their Extra Deck and are the only ones to control a Tribute Summoned Monster, the opponent can not Special Summon Monsters from the Extra Deck