Originally Posted by Ycore
I agree that a BV is generally better than a FoN on irelia, however the FoN builds from a Negatron cloak, which is usually the first thing I buy after a Trinity. It's cheap, and helps so much against a variety of casters. To be honest, BV sounds great, but i always find it pops on someones cruddy Q, rather than their R. The only time I find a BV to be super valuable is against Karthus, as it eats his annoying global ult. It's kinda like a QSS against Malz/Warwick, situational, while a Negatron cloak is just plain always useful for the gold price.
You are aware that BV also builds from a Negatron Cloak, yes? What makes BV better than FoN for many champions isn't just the spell shield -- the additional HP makes your MR go further, and more Mana lets you use your abilities for extended periods. Yes, the shield is easy to counter provided the enemy has the means to stop it, but having the shield at all is a deterrent, and it will help against certain champs more than others.