is always updating its classes, which changes how strong each class and build is in different seasons. Season 7, the Season of Witchcraft, introduces Witchcraft Powers, which synergize better with some builds than others.
However, using them provides a power boost to every build, even if it isn't the best to use this season. But if you want to wipe out Whispers in Season 7, the Cataclysm Druid is a build you need to at least consider, as it's one of the strongest.
The Cataclysm Druid is ideal for endgame content in Season 7. You have immense clearing and farming potential due to the amount of area damage you can deal, and you can withstand being in the middle of enemies with the help of a few defensive skills.
The end result is a character that blends offense and defense so effectively that you feel unstoppable as you rush through dungeons and complete world tasks.
For builds like the Upheaval Barbarian, the focus is centered on a core ability. That's not the case for a Cataclysm Druid, as Cataclysm is an ultimate ability instead of a core one, which means that putting this build together takes a bit of time if you start it at Level 1 rather than respec into it later.