Base Upgrades are perks that help bolster the defenses of a player's base their are at least four types of upgrades which are listed below.

• Guards: Every two levels gives your minions additional health and armor

• Economy: Doubles Diamond production along with diamond storage

• Sentry Gun: Every Two levels gives your sentry gun more health and armor

• Player Health: Increases Base Commander health for extra survivability

Notes

• Always upgrade Economy during Base Alpha and Base Bravo stages before upgrading anything else as your going to need the extra diamonds for weapon upgrades.
• Keep your guard levels high, about 4-5 levels above your current level, because there's a good chance someone 3-4 levels higher than you will attack and steal your diamonds easily.
• Player Health is useless in base defense, but helps to increase your health both in campaign missions and in PVP defense. Better to upgrade it after Economy and Guards.