When cascading blight, can you choose a land protected by Infinite Vitality, or does the protection mean that you have to cascade somewhere else?
In other words, can you use Infinite Vitality as a cascade sink?
You can indeed use a land protected by Infinite Vitality as a cascade sink!
You can also, eg, target it with Powers which add Blight, or choose it as a land to Blight for certain Events or France's Stage 2 Escalation effect. It doesn't restrict in any way your ability to choose to add Blight to that land, merely what happens when you do.