Nebulous
Legend
To be a success the D&D movie has to look good, have decent trailers, and be entertaining enough that people tell their friends to see it and it builds decent buzz.
How do you do this? You do what Thor: Ragnarok did. You make it look entertaining and fun.
This is the goal of every trailer for every movie every made. Have you seen the critical buzz about Captain Marvel? The internet is BASHING the next big marvel tentpole movie based on how poor the trailers have been. I can't say if it's a bad movie or not, but based on the million dollar trailers, I'm not inclined to watch it.
To be fair, I hated the early Ragnarok trailers, but when I saw it, it become my top 5 Marvel films.