You can see all the set's currently revealed cards in our Adventures in the Forgotten Realms spoilers guide - and make sure to check back regularly, as we'll be updating it frequently once the set's preview season of daily reveals begins on Tuesday, June 29
I really want to thank the Commander Format Panel for their hard work here: they have been putting in a ton of time discussing, debating, and working toward conclusions on all of this
Making board wipes cost more mana is a way that white can gain card advantage and keep its board, and whether thats in constructed or in Commander, its a valuable ability
I think its good to play three sometimes, mostly when your artifact count is looking low because of various colored cards in your deck, but I dont think Id ever play four again unless I was looking to build a dedicated swarm version
For 2 green and 3 generic, you get a 4/4 Legendary Dragon Spirit with the following abilities: Flying Deathtouch When Kura, the Boundless Sky dies, choose one: Search your library for up to three land cards, reveal them, put them into your hand, then shuffle
It greatly enhances decks built around the Worst Generation (Supernovas) and Donquixote Family (Dressrosa), among others