Consumables, as the name suggests, only last for one battle. There are a couple of fun ones which give you a very short time effect, or allow you to build a trap or barricade. But there are also consumables which simply increase your stats for the whole duration of the battle. You can set those to auto-replenish, and get the effect in every battle, at the cost of silver. As a result, with a premium account you can play with consumables all the time and not have any money problems. With a free account you can only afford them once in a while. So in the end the premium players' units have better stats than the free players' units. But it is very discreet and not widely advertised. Hidden Pay2Win.