You can use Gateway to Chaos to get Black Luster Soldier into your hand, and spell card later on after 3 spell counters. Beginning of heaven and earth can also be used to add Black Luster Soldier to hand or mill him to the graveyard.
Super Soldier Synthesis is a more cost efficient way to ritual summon Black Luster Soldier, but requires more specific tributes. Additionally can be used to ritual summon a Black Luster Soldier in your graveyard.
Forget it, he used Djinn Disserere of Rituals, that made it inmune to SSA.. nice combo.
I love this card, but on it's own it does not deserve UR status. They only did that so it could be the cover card of it's box cause it's a recognizable classic card, but on it's own the card isn't that good, and wouldn't be worth the gems and money spent to get multiple copies if he doesn't get more support soon. And even if he did, good support is only good if you can actually get multiple copies of the card easily, which you can't.
Given they gave us Super Soldier Synthesis, you don't really NEED multiple copies, since it can Summon from the Graveyard. (And if you're using Black Luster Ritual instead, you might's well use a stronger Ritual Monster like Masked Beast or Shinato anyway.)
Why is this card a UR and Magician of Black Chaos is Rare.
Because they wanted it to be the cover card for it's box because it's a recognizable card. Making it an UR makes pretty much no sense because it's not a good card on it's own without support, and to effectively use it's support you'd probably need mutltiple copies, which is a shame since there's only 1 of him in each box and pulling him every time you reset the box is gonna be incredibly expensive
It must because it seems like a costly ritual bewd with way worse support cards. I don't see the point of ritual monsters that don't have effects. Sure you have a high attack guy but u just die to mirror wall.