Deciding the first post-Duelist Alliance card to discuss for this week was difficult because there's just so many cool options from the new set. This week's card, Doomstar Magician, is a prime candidate because literally no one anywhere is talking about it, but it could really shoot up in price down the road. It's essentially a Number 103: Ragnazero for Pendulum Monsters, and that's crazy. A successful resolution of its effect not only pops an opponent's Pendulum Monster, it also gives you a free card.
Of course, it's important to note what you can play it in. In general you're going to leave Doomstar Magician in the Side Deck, ready to take out Pendulum-based strategies. In reality though you can run it in almost any strategy, because the activation requirements are extremely easy to pull off and don't involve any jumping through hoops. Specifically speaking, I think Doomstar Magician best fits in Spellcaster decks like Spellbooks, and I wouldn't be surprised to see Spellbook duelists using them in the near future. The Magician could become incredibly important as Pendulums get better, and it might be a smart investment while they're affordable.