I will post a longer guide if people are interested in one.

Quick guide:

Play murlocs in the early game, and elementals in the mid / late game. Heal with Cookie the Cook Canal Slogger. Close the game by poking the enemy down or freezing the board with Snowfall Guardian.

Vs Warlock:

Don't try to kill him early on, Warlocks have too much board clear. Use the healing from Cookie the Cook and Canal Slogger to survive the curses in the late game, then kill them.