Questions regarding Legendary Banner

heard it was L!Ghast...not sure tho

Just one new legendary, they said the next mythic unit will come in late January of 2019.
Probably getting a trailer tonight as they're usually released a day or two in advance of a banner, although there's probably been a few expectations to this.
As for, who it is, no one really knows but theres a decent chance for Alm or Seliph since we've been asking for them.
The banner does drop on Friday at 2:00 AM (EST), theres also a countdown at the homepage near the bottom which should help