A new day brings more goodies in Fire Emblem Heroes and also a new Grand Hero Battle. This time you will be going up against Zephiel: The Liberator. There is also a new Summon focus that could net you 5* versions of Hana, Reinhardt, Frederick & Nowi, who will prove useful in the Grand Hero battle. Below are screenshots of the In-game Notifications and the Heroes of the latest Summoning Focus.
Source: Fire Emblem Heroes (In-Game Notification)