Whirlwind is very breakable with certain relics and enchantments. Put Vigor 8 on this and draw it off Offering and most fights in the game will already be won or close to it. I think it's more worth picking up in Act 1 if you're going to some events, for the chance of it becoming very strong very quickly, but you'll definitely also have runs where you never find a way to make it much better, in which case it's not a great card. Often worth upgrading if it's worth taking at all.
