So the Feh Channel about the 2nd Anniversary event just casually dropped onto Youtube just now! It's a video instead of a stream.
Main pointers:
-A bunch of rerun banners from past BHBs will run during the first two weeks of February.
-2 Banners that will give you a guaranteed 5-star unit. One banner features all the seasonals from 2017. The other features all the seasonals from 2018. You'll choose your 5-star unit from each of them based on the color of their orb AND it's a one-team deal for both. First banner starts from February 1 until February 8, and the second one starts from February 8 until February 15.
-Find & Vote Heroes: a new website mini game that will allow you to vote for a unit by first selecting their color orb, then having to find them on a map to cast your vote. If you find the Askr Trio within the first 180 seconds of playing, you'll add a bonus vote for the Hero you voted for. You'll also get a special wallpaper depending on how much time you have remaining after you voted. Lasts from February 3 to February 8.
-2nd Anniversary Heroes Summoning Event: The number one hero for each type (presumably these winners will be decided from Find & Vote Heroes) will appear on this banner. You can choose which one to summon for the first summon like the CYL banners. The banner will last from February 24 to March 3.
-Dragonflowers: These will allow you to increase your hero's stats. There are four kinds of them, each oriented toward the type the hero is (Infanry, Cavalier, Armor, and Flier). They can only be used up to five times, but Infantry units can use them up to ten times (good, because infantry characters tend to be outclassed these days). The increased stats will also have no affect on Arena matches.
Heroic Ideals: New mode that has specific challenge quests for certain characters, and you can only access those quests if you have the respective character because you are required to use him/her. This mode is also how you'll get more Dragonflowers.
Aether Raids updates: Aether required for battles is now cut in half, the maximum Aether required for battles caps at 50, and first battles of the day are no longer free. The maximum tier has also been increased to Tier 27. When an Aether Raid season ends and you are Tier 22 or higher, you automatically reset to tier 21.
Merge Allies updates: This one we already knew about already, though they did mention that already merged units will also gain access to the bane removal with the subsequent merge, so that's cool.