The EU Summer prelims will be played out over the 13th and 14th August
2016. You can watch all the action on the Hearthstone Twitch Channel.
Here is the RDU EU Summer Prelims Yogg Druid Deck he will be using to try and advance to Blizzcon. Remeber, tournament decks are not always the strongest ladder decks, but there is a lot you can learn from playing with these decks.
Yogg token Druid is probably the strongest overall deck right now. I expect almost everyone will bring a version very close to this one. I prefer the version with Cenarius personally, useless you are synergizing Onyxia with Wisps of the Old Gods. But this deck is obviously working well for RDU, so we will see how it does in the Prelims.