Phases

Build Phase

Once inside the map, you'll start off with the Build Phase. All green crystal chests will become available. Each map will have four chests for each player. If there's lesser number of players in a map, they can only loot one chest. This mode, you can instantly build, repair, or upgrade your towers. Don't place your defenses near the border. An enemy that can throw projectiles can outrange your towers from behind the barrier, rendering them vulnerable and they won't be able to fire back.

During the Build Phase, you can also freely switch between any of your heroes in your Hero Deck by accessing the Defender's Forge. You'll have Build Phases between every enemy wave. There will be timer before the Wave starts or every player can press G to start it early.

Combat Phase

This is where enemies will start their assault and arrive simultaneously in any of the multiple instances. Basic strategy requires at least one player guarding each entrance during the onslaught and move in to reinforce their allies once the entrance they're guarding is clear of enemies. For heavily defended entrances, sometimes player intervention is no longer needed, except for repairing or attacking.

You can still build, upgrade, and repair your towers. However, they'll be slower and you won't be able to use the other functions until the action you selected is finished. Also, you cannot change your hero in the middle of a Combat Phase.