Opening the battle palette stops time and gives you access to the character’s alchemic spells on the left side and item pouch, grenades, and secondary weapons on the right. The spell and item assignment of the character’s battle palette can be modified before starting a mission or when you're inside Basil's Factory so make it a habit to check if your squad members are properly equipped.
While in the Battle Palette screen, you'll be able to see the selected spell or item's description and other useful data like what status effect they cause, their damage, and their effects. Knowing some of these details by heart will come a long way in helping your strategy at any given situation.
Guns and grenade have limited ammunition. These can only be replenished by capturing an enemy base or outpost. You’ll unlock more secondary weapon types like machine guns, launchers, and sniper rifles later on. It’s also worth upgrading your secondary weapons whenever available.
Items are shared among all members of the squad so make sure to have an ample supply of various health and recovery items.
From the battle palette, you can also issue order specific members of the squad to perform a particular action. You can use this option instead of switching over to the desired squad member.