He had soul magic, it quite nicely explained.
Misteltein wand is already with Brynhildr. We will get to Solomon's rings.
Yes.
We will see, the first chapter of the next volume will clear a lot of things. As for multiverse, probably no.
Think again!(Spoiler!)
The fruit of patience is sweet.
Who is dead?
Eresh is alive and doing well, the reason will be explained when she makes an entrance.
3. The sumerian pantheon lost its divine domain and got destroyed.
Anime & Comics · Vegeta_Kakarot
Trihexa will be used in that way, just that it is a bit later in the story.
1.) Great Red, Ophis and Trihexa are at the same level. GR knows how to use his powers while Trihexa is a mad beast. Ophis doesn't know either. She is dumb.
Anime & Comics · Vegeta_Kakarot
He didn't use death magic, he primarily used darklight in the form of a scythe with some help from the Scythe of Azazel.
As a Lucifer in DxD
Anime & Comics · Vegeta_Kakarot