Onyxia is easy right now.. do it before Blizz decides to nerf Anub'arak

The tactic is simple:

Survive the first 30 seconds with a big push, then block/make anub stuck at base with the stationary skeletons.

Then survive until overtime. Make sure to build lots of stationary skeletons around base so they can stop any enemies approaching.

Then at overtime spam your units with beetles onto Onyxia and kill her.

Can be done with a lvl 21 team.

Most play bats instead of harpy due to lower cost, I only used harpy because my bats are not leveled.