The amazing world of "Final Fantasy XV" is filled with beasts, treasures, and intense battles. It is a must to have and use these items well in order for Noctis and his friends to fight and survive.
First, have a sufficient stock of Magic Flasks. This is where you will store the Elemancy such as Ice, Fire, and Lightning as well as other items to craft magic spells. The more crafting skills you create, the more number of elemancy and items that you would need to store. Also, you need to raise the potency your elemancy to above 100 to make it a higher level. For excellent magic spells, combine all the Elemancy with the Catalyst to create powerful effects. Furthermore, use the Ascencion Grid very well so that you can bring more magic spells in battles.
Second, buy a lot of Potions instead of Elixirs. Potions are very useful whenever Noctis hits critical health or danger mode since these have healing properties that can restore HP to its half percent. On the other hand, Elixirs are also useful during critical damage although these are more expensive compared to Potions. Elixirs can restore both HP and Magic Power to 100 percent and regenerate HP to 50 percent. It is advisable to buy less of these since these can be obtained by completing side quests and doing several bounty hunts.
Lastly, Phoenix Down is also best to have before going to difficult battles. Phoenix Down is very useful to revive Noctis' friends once they hit danger mode during battle. Unfortunately, it does not provide a full recovery. And so, it is recommendable to use other special items or retreat and make camp to help them recover. Remember to always pay close attention to Noctis' friends during battle since they are vital to complete any quest.