You don't have to attack with the creature with dash unless another ability says you do
None of the other, similar hate cards stops all three of these tier decks, which should make Soulless Jailer a popular sideboard option, especially for decks with artifact or creature synergies
Noble Hierarch Another one whose reprint ( Modern Masters 2015) didnt seem to do much to increase its availability and lower cost, everyones favorite Bant mana creature is certainly going to find its way into a number of decks that didnt have it before
Since it's mana free, you can use it when you've tapped out, or cast a mass removal spell like Damnation or Life's Finale to save it proactively not reactively to something else and have the only creature left on the battlefield
It's not as good for go-wide strategies as other protection spells like Divine Resilience (an uncommon from this same set!) will be a better contender there, but go-tall strategies will love this