Hello to one and all!

[Obi2Kenobi]

That equals up to 100 points.
I have spent 5 on prerequisits to get Whirlwind already, so the last 5 will be spent like this.

1 - Into Berserk

I think you should get Berserk at level 30-35. This way, in case of a Physical Immune, you can beat it. :) And it only costs 2 mana at level 1, so you can use it against the enemies for quite some time.

Today I hit level 30 after finishing the third quest in Act V, I got Whirlwind, which does not seem that great. To much mana and the - 50% damage does not help at all. I know it will get better at higher levels, so I am not giving up on it yet.

I've found that your 1 point in Concentrate is much better than whirlwind until you get a few points into it. Also, you're going to need either a lot of mana potions, or a mana leech weapon if you want to use Whirlwind as your main attack.