Wanted to cc: in a quote from @JACO in another thread, for reference: The far more devastating effect of the Thorn of Amethyst restriction is to White Eldrazi. Thorn + Thalia was the basis for that deck to begin with, so I think now is the time for those White Eldrazi decks to widely adopt Null Rod/Stony Silence, as well as fully integrate Sanctum Prelate in to their builds, and change their manabase slightly to accommodate the necessary change. I played a fair amount of Prelate in the end of 2016 and early 2017 (in both Eldrazi and Junk Hatebears decks), and it is as good as advertised, if you can cast it on time.
When I last played the deck pre-ban, I had gone down to 3 Temples and upped the basic Plains count to 5, in addition to the 2 Karakas, for non-Cavern white mana sources.
Is it time to start playing Caves of Koilos in the deck as well since there is still some synergy with the Eldrazi colorless requirement? If so, is 2, too many? I hadn't thought of the Sanctum Prelate option to this point but it's such a great idea (if it can be cast consistently), although a turn slower than you would often want to be.