Nightcrawler is only really playable in an X-Men deck, but he can fill a nice role in the X-Men shell. At a total cost of 4, you get 1 use of a 2 power attack or thwart and a 'block' that returns Nightcrawler to your hand. While it might seem inefficient, consider that is a reactive block that you can save for a massive boost card or surprise overkill or piercing attack. The normal way allies block is proactive, which means you sometimes block only a 2 or 3 power attack that your hero could have just taken. Protective Training makes Kurt a decent thwarting option in an aspect light on options. Other X-Men archetype cards like Danger Room and Utopia turn any average X-Men ally like Kurt into an all-star. In a dedicated X-Men deck, you can feel very comfortable giving a spot to Nightcrawler. If your hero doesn't have the X-Men trait, there is no reason to play this card.