The Ghostbusters (Drs. Ray Stantz, Peter Venkman, & Egon Spengler as well as Mr. Winston Zeddemore) are hired to try to take down the feared Morsayati/The Other of Dragalia Lost.

(Morsayati's origins are revealed during the Forgotten Truths raid event, which is actually canon in regards to the main story campaign; he is basically spoilers:
the "physical" manifestation of the anger & hatred of the welfare unit of this event, Mordecai
end of spoilers.)

Round I: The Ghostbusters try to stop Morsayati during the First War of Binding (Forgotten Truths), with or without the aid of all parties involved in this battle.

Round II: The Ghostbusters try to stop Morsayati during the Second War of Binding (Dawn of Dragalia), with the express side mission of preventing Alberius from needing to undergo the Blood Casket ritual.

In the event that the Ghostbusters have any trouble containing The Other, they can call on their various counterparts as backup (such as their IDW counterparts, their Extreme Ghostbusters successors. and the 2016 crew).