We all know that The Vault is our best(and only)place to keep our old and not used monsters. But at some point become very expensive to buy with gems new slots.We can use keys of course but we must have high level to have a lot of keys. Now in the game are a lot of monsters and some players are colectors and they not feel good to sell monsters to make room for new monsters. Soo...my ideea is kind of simple. In the next update for game to put the next feature : For every war won besides the usual rewards,all players inside that team to get 1 key for monster vault Slowly but for sure,in time,players will gather enough keys to unlock how many slots they need to keep all the monsters.