The best way to understand the game is to understand the abilities of the cards.
Understand the combos and to see which cards works with the other and how to use them.
Class Benefits
This is the chart which will help you in the game gaining additional 15% damage against the other classes. Most of the games that you would be playing in the arena (PVP) will have plant class in so if you have a beast, bug or mech axie you can gain additional 15% damage.
Nut crack has an attack damage of 105 and 30 shield. If you combine this with another nutcracker card you deal 120% damage.
Nut Throw has an attack damage of 105 and 30 shield. If you combine this with another nutcracker card you deal 120% damage.
Now if you have both of these nut cracker abilities and you go against a class for example plant you gain additional 15% class bonus which now combined Nut Throw and Nut Crack can deal 135% damage to the opponents axie.
How to use
Always go for this combo if you have one energy left wait for the next round once you have 2 or more energy. Don't waste your 1 energy by playing either one of these cards as a single card they will do normal damage but if used both of them as a combo you will have benefit. Sometimes this combo could be the difference between losing or winning the game. So play wisely.