Snowball Effect

Snowball Effect: Hit 10 different minions with a single cast of Snowball Fight!

This is one of the hardest achievements to get, it's not hard to see why, not only there have to be at least 10 minions on the board (So at least 3 minions summoned by your opponent), but since the effect is entirely RNG dependant the snowball can go back and forth between two minions and whiff.

The idea: We need high health minions on the board, doesn't matter if by our side or our opponent's. The only reliable way I found to get to such a state is a Shudderwock Shaman that locks your opponent from playing while you try to setup the perfect board for Snowball Fight! by repeating the battlecries of Marin the Fox to summon several 0/8s on your opponent's side and Mankrik+Primal Dungeoneer+Grumble, Worldshaker to fill our hand with 1-mana 3/7s.

The gameplay is the same as any modern Shudderwock shaman, stall the game until you play the key battlecries you want to be repeated by Shudderwock. 

On the first combo turn play:

• Tour Guide
• Hero Power (Heart of Vir'naal)
• Shudderwock

If you did everything correctly you should have a 1-mana Shudderwock in your hand (courtesy of Grumble's battlecry) and, thanks to the effects of minions such as Snowblind Harpy, Antique Healbot, Reno Jackson, Snowfall Guardian, Loatheb you should be pretty much unkillable from this point on.

The following turns you can begin setting up for the Snowball turn.

• Try to kill any low health minion on your opponent's board.
• Keep spamming Shudderwock until your opponent only has decently sized minions and Master Chests
• Once the opponent board is full, play the Mankriks you have in your hand (as many as you can) leaving 3 mana for Snowball Fight!
• Play Snowball Fight! on the highest health minion.
• Cross your fingers.
• Hopefully you completed the achievement!

Personally it took me a couple games to manage to get to the combo turn, but I got the achievement at the first attempt.