First, you need these cards. Make a deck with these, and fill the rest with anything you have (more copies of the same cards better).

1 x Squirrel Ball
3 x Skeleton (or any other 0 cost tribute fodder)
1 x Urayuli
2 x Wolf Cub
1 x Mantis God

Next, you need to pass turn until you draw all these cards, and then, follow the steps:
1. Play the Squirrell on the left
2. Wait for the Squirrel to fill all zones
3. Play Urayuli to the left
4. Summon 3 Skeletons, tribute for mantis on place 2, and the two Wolf Cubs to the right, places 3 and 4
5. Done! This will deal exactly 14 damage every time

Check screenshots sections of this guide

Hope it helps :)