Depending on how low of a level and how much you have invested in game you could reroll day 1 of the FF1 event for Warrior of Light. This way you can start fresh with an awesome unit and spend your visiore getting his shards. When the tower comes out again you will have an easier time with a tank.
He should be out next month. There is a more info under the tier list section if you want to check out his abilities. Keep in mind you will need 30k visiore to max him out. We should be getting some shards from hard quest and visiore spending so it may be less. Hopefully we get a free 10x pull so you can reroll till you get him and spend the remaining visiore on his shards.