X-Force #26 was the issue. Nightcrawler manages to whisk the prophesied mutant messiah Hope Summers to the island Utopia, but not before receiving a mortal wound from the sentinel, Bastion. So long, Kurt. You've had a long run. Many have come and gone since your first days with the X-Men. They often say that you can't come back from a robotic arm impanted through your chest. But take heart (*ahem*). Many of your teammates and enemies alike have suffered much worse fates and come back to fight the never-ending battle. Godspeed.