Kobold Miner is the card which you should use at every battle. With sneak ability he always attack to the last standing monster. Main advantages of this card are : It just costs 2 mana to deploy this card which is great especially if you have 2 mana space left, sneak ability will help you to destroy opponent's monsters at back positions, his speed will let him to not miss his chance to hit the enemy, his health is normal to resist against enemy attacks. Fortunately l couldn't find any disadvantage for this card.
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From @smalien