When you receive Heroes, Weapons and Loot in the game, a notification will pop up - or if you are not in the game, when you login - detailing each item that you have received.

Please note - if you are in the middle of a battle or on the map, you will not see the pop-up until you come back to base.

In case you missed the pop-up notification before seeing the items that you have received, you can also check by:

Tapping Menu > Inventory

The same thing is applied to Heroes and Weapons. You can check that the new Heroes have been added to your Roster by:

Tapping Menu > Roster > Heroes

You can check that the new Weapons have been added to your Roster by:

Tapping Menu > Roster > Weapons