https://www.pcgamer.com/the-next-card-reveals-for-hearthstones-the-witchwood-will-kick-off-next-week/

Hearthstone's next expansion, revealed last week as The Witchwood, will feature two new keywords, Echo and Rush, a Dungeon Run-style game mode called Monster Hunt, and 135 new cards. Blizzard announced today that the process of revealing those cards to the world will kick into high gear (since we've already seen a few of them) during a livestream on Twitch set for March 26. 

Card reveal duties will be shared with various press outlets and members of the community in two separate rounds, the first starting at 3 am PT on March 27 at 17173.com and the second at 7 am PT on April 2 with YouTube streamer Tomatos. You'll notice that 17173 is a Chinese site (which also accounts for the odd timing), while Tomatos is a Russian streamer; Korean and Brazilian sites and/or streamers will also be taking part.